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Inherited New Features.

TNTview 7.0 provides all the following new features introduced in detail in the corresponding sections below for TNTmips.

System Changes.

Hundreds of new Coordinate Reference Systems, datums, datum conversions, and related features make up the Open Geospatial Consortium (OGC) Spatial Referencing System used in the ISO 19111:2003 Spatial Referencing System standard.  These include all the Coordinate Reference System (CRS) definitions of the European Petroleum Survey Group (EPSG) all of which are updated biannually.  These are now all incorporated into TNTview in addition to those developed by MicroImages for previous use with your imported or linked geodata.  The map calculator can also make all these new kinds of conversions.

Shapefiles and their styles, projections, and other characteristics can be selected and automatically used in TNT processes and as display layers.  These auto links are much faster in RV7.0 as they are now made via the TNT shape object rather than via a CAD object as in V6.9.  Now you can also use the Spatial Layer Controls to add TNT features to be used with the linked shapefile, such as new styles and groupings and DataTips.  GraphTips, virtual fields, implied one-to-one table linkages, new tables, and all the advanced features and properties you expect to have for any geometric data layer in a TNT product can be set up from the Group or Layout Controls and saved with the link to the shapefile.  Since these advanced properties are stored in the shape object link file, the shapefile and its table are not altered in any way although the originally associated table can be edited in a TNT product or ArcView.

The compressed size of all compressed rasters can now be larger than 4 GB if permited by the format’s specifications.

JPEG and PNG compressed rasters can now be selected and automatically used in processes and as display layers.  Their georeferencing and CRS information is automatically built for them in the link to make their subsequent display and use as fast and efficient as internal raster objects.

All compressed ArcGrid files can now be imported.

Importing non-topological datasets (for example, shapefiles, DXF, Oracle Spatial layers, …) into a vector object applies all the improved deconflation operations as part of the automatic topological validation procedure.

2D Display.

Your LegendView has styled legend entries for a linked shapefile if its AVL (ArcView Legend) file accompanies it.  When no AVL file is present, legend entries are all in a single solid color.

CAD layers can now have the same advanced label styling, frames, leader lines, and other features as those used in vector layers.

CAD layers can now have all the many new DataTips, Enhanced DataTips, GraphTips and associated Display Control Script features described below in detail for TNTmips.

Linking to and importing from MrSID files in V6.9 was the only significant TNTview feature unique to a Windows system. Now new libraries from LizardTech also make this feature available in TNTview for the Mac OS X operating system.

Text annotations can be added in anywhere in the sketch layer overlaying the view.  A sketch layer is a CAD layer and can be saved as CAD object for future use in TNTview or the other TNT products.  Since this is a CAD layer these annotations are actually labels and can have the same frame outlines with background colors/transparency and multiple leader lines.

3D Display.

3D views now use only the advanced rendering methods that now all offer the advanced features of the older, slower, lower quality rendering methods, which have been removed from RV7.0 of TNT products.  Some of these new features of the 3 new, high-quality 3D rendering methods include direct relief shading, layer transparency, and smooth color/transparent pedestals and fences (upward pedestals) both of which can follow around 3D surfaces with curved edges.

Multiple manifold layers can be vsualized in 3D views with or without surface views.  A manifold layer is a raster, vector, shape, or CAD object with 3D georeference that is draped onto a continuous planar, curved, or irregular surface of any orientation in space that can be defined by a collection of 3D coordinates.

Maneuvering around a wireframe representation of the terrain to select an initial 3D observation position is now much faster.

Stereo Display.

Complex multi-layer 2D and 3D views of terrain surfaces and/or manifold surfaces can be converted into high quality stereo views.  These stereo modes now include separate frames, column interlaced, line interlaced, and anaglyph to support the use of almost any available popular stereo viewing device.  High quality stereo viewing can now be done with a mirror stereoscope using one large or a pair of flat panel monitors and also with the new stereo flat panel monitors that do not require glasses or any other external viewing aid or device.

Rendering of images into stereo views with parallax computed directly from the terrain layer is now faster since they no longer need to be draped on the terrain.  This also improves the image quality for stereo viewing.

Importing Geodata.

New vector imports include CARIS ASCII and improved font support for MapInfo.  New raster imports are MrSID on the Mac and compressed ArcGrid.  

Customizing.

As usual the extensive additional features added to the TNT cross-platform geospatial scripting language (SML), such as those to create manifolds and new Display Control Scripts for creating GraphTips, are available for use in your scripts to create special tools, display effects, processing features, and so on. 

The TNT Software Development Kit (TNTsdk) is now available FREE with every RV7.0 TNT product including TNTview.  Now you can add your own processes to your TNTview menu or anyone else’s using all the C++ functions and classes used to build the TNT products.  For windows you will be working with Microsoft’s C++ compiler in Visual Studio .NET 2003, Professional Version.  You can compile the same program for use on the Mac, Linux, and Solaris using the current version of GCC.  

Please be aware that the SML and TNTsdk export functions and classes are not available for use in TNTview to export geodata for use in other products.

Upgrading TNTview.

To a Different TNT product.

Any TNTview can upgraded by its original purchaser to a TNTedit or TNTmips with full credit for its original purchase price (for example, US$500, US$1000, or US $1200) after it has been upgraded at the very low price noted below to the current version of TNTview.

Upgrading from an Earlier Version.

If you did not purchase RV7.0 of TNTview in advance and wish to do so now, please contact MicroImages by FAX, phone, or email to arrange the purchase of this version. When you have completed your purchase, you will be provided an authorization code by FAX.  Entering this authorization code while running the installation process allows you to complete the installation of TNTview 7.0.

Fixed License.

The prices for upgrading a fixed license to RV7.0 from an earlier version of TNTview purchased at the earlier higher prices are US$50 from V6.9 or US$100 from V6.8 or any earlier version.

Floating License.

The prices for upgrading each seat on a floating license to RV7.0 from an earlier version of TNTview purchased at the earlier higher prices are US$60 from V6.9 or US$120 from V6.8 or any earlier version.

Future Upgrades to TNTview.

Fixed License.

The worldwide prepaid price for a minimum of 2 or more future upgrades for TNTview will be $50 per each version.  For example, purchasing your upgrades now from RV7.0 to RV7.1 and to RV7.2 will be US$100. 

When TNTview 7.1, RV7.2, or … are officially released, upgrades to any current version from any earlier version (RV7.0 or earlier version) will be US$200.

Floating License.

The worldwide prepaid price for a minimum of 2 or more future upgrades for TNTview for each seat will be $60 per each version.  For example, purchasing your upgrades now from RV7.0 to RV7.1 and to RV7.2 will be US$120 per each seat, which is each simultaneous user. 

When TNTview 7.1, RV7.2, or … are officially released, upgrades to the current version from any earlier version (RV7.0 or earlier version) will be US$240 per each seat, which is each simultaneous user.

TNTedit™ 7.0  

Inherited New Features.

TNTedit 7.0 provides all the new features summarized just above in the section Inherited New Features for TNTview.  The following additional new features not available in TNTview are summarized here for TNTedit.  All these new features in TNTedit are introduced in greater detail in the corresponding sections below for TNTmips.  

Georeferencing.

Manifold surfaces can now be created by adding 3D georeference points to a raster, vector, or CAD object to define a manifold object for 3D displays.  These point positions and connections can also be edited to shape the surface.  There is a detailed discussion of manifolds and their use in a section below entitled Manifolds. 

Control points can now have names and IDs.  Resampling from geographic (latitude-longitude) coordinates can now create cells specified in degrees/minutes/seconds.  The pyramid computation method for an output raster object can be selected from None, Average, Sample, and Automatic.

Editing.

You can now copy from vector, CAD, TIN, region, and linked shape objects (for example, a linked shapefile).  During the copy operation, you can now select the irregular area to copy from any of these geometric objects using a region object.  This copy area selected from a vector, linked shape, CAD, or TIN layer can be optionally controlled to be Partially Inside, Completely Inside, Clip Inside, Partially Outside, Completely Outside, or Clip Outside the region object.

Regardless of the type of geometric object selected for the copy operation, this sub-area can be pasted into a vector or CAD object.  If pasted into a vector object, its topology and database structure will be automatically reconciled (validated) in the target vector object.

Right Mouse Button operations will now allow the toggling through nearby elements (not just vector element types as in previous TNTedit versions) for vector and CAD editable objects.

Manifold object geodata content can be edited in a 2D view and the results viewed in a concurrent 3D view.  

Database Table Setup.

A simple wizard approach is now used when you set up a new table and its relational linkages.  This includes setting up virtual tables.

Exporting Geodata

Geographic Markup Language (GML) can be exported from CAD or vector objects.  CAD or vector labels are exported to shapefiles.  Exporting raster objects to PNG, TIFF, and GeoTIFF files have improved support.

Exporting geodata via the SML and TNTsdk export functions and classes are available in TNTedit to use to create geodata for use in other products.

Exporting Via Scripts.

Tool and Macro scripts started in TNTedit now have the ability to use the MicroImages Import / Export SML classes.  For example, your special selection tool implemented in a Tool Script could select features and export their results directly to any supported external format while also using all TNTedit’s functions to prepare these features. 

Geospatial Scripting Language (SML).

Tool and Macro scripts can use the Import / Export classes for SML scripts run within TNTedit to output edit results to custom formats.

Upgrading TNTedit.

If you did not purchase RV7.0 of TNTedit in advance, and wish to do so now, please contact MicroImages by FAX, phone, or email to arrange to purchase this version. When you have completed your purchase, you will be provided an authorization code by FAX.  Entering this authorization code while running the installation process allows you to complete the installation of TNTedit 7.0.

The prices for upgrading from earlier versions of TNTedit are outlined below.  Please remember that new features have been added to TNTedit with each new release.  Thus, the older your version of TNTedit relative to RV7.0, the higher your upgrade cost will be.

Within the NAFTA point-of-use area (Canada, U.S., and Mexico) and with shipping by ground delivery. (+$50/each means US$50 for each additional upgrade increment.)

For a point-of-use in all other nations with shipping by air express. (+$50/each means US$50 for each additional upgrade increment.)

Tutorial and Reference Booklets

There are now 77 TNT Tutorial and Reference booklets.  These booklets provide more than 2000 pages and over 4000 color illustrations.  The most important of these booklets are up-to-date with the features in RV7.0 of the TNT products.  However, others still show minor differences primarily in the user interface layouts of earlier TNT versions.  Additional revised booklets will be provided as completed for your downloading via microimages.com. The new booklets provided with this release and those with significant additions are illustrated and summarized in the accompanying color plate entitled New Tutorials.

Each new professional TNTmips ships with 3 thick notebooks containing a color printed copy of these 77 booklets.  Those of you receiving your RV7.0 upgrade on CD can view and refer to all of these booklets using Adobe Acrobat or Reader.  If you install all these booklets as part of any TNTmips product, you can directly access these booklets from the Display menu, by choosing Help / Tutorial Overview and selecting the booklet, or via Help / Search and using the index this provides.

New Booklets Available.

Working with Massive Geodata Objects.  (printed copy provided)

Large geodata sets are available or you are assembling them in TNTmips.  This booklet provides advice on how to structure and maintain them for optimal use in the TNT products.  Individual rasters and mosaics can use appropriate compression and a null value mask.  Compute standard attribute tables (for example, area, …) only when needed.  Merge contiguous vector objects to eliminate management and fragmentation of many pieces.  Merge line and polygon objects when they need not be kept separate.  Dissolve out unnecessary polygon boundaries.  Remove excess nodes.  Thin down vector lines.  Maintain a simpler topology if possible until full polygonal topology is required.  Transfer attributes to simplify relational databases and remove duplicate records.  Setup the viewing scale for the range of interest for objects.  Use DataTips and GraphTips to simplify views rather than turn on many simultaneous layers.  

Introduction to Using TNTsdk.  (printed copy provided)

As discussed above in detail, TNTsdk is now available free to develop additional geospatial software for use with TNTview, TNTedit, or TNTmips.  This brief new booklet introduces you to some of the things you should consider, such as getting support, cross-platform issues, and how to ensure that your program can be localized or translated for use in your language.  It gives some suggestions on how to set up your TNTsdk programming environment and keep it updated and current.  It also discusses a sample program included with the TNTsdk. 

Orthorectification Using Rational Polynomials.

TNTmips now provides a simple procedure to produce orthorectified images from full or partial QuickBird and IKONOS images ordered as Rational Polynomial ortho ready kits.  This procedure requires a good quality DEM of the area covered and several well distributed, accurate XYZ ground control points (GCPs).  This new booklet covers the procedures available in this new process.  It outlines how to obtain and evaluate GCPs and test points of varying quality.  Significant modifications of the TNT georeference procedures were required to enter and use these XYZ GCPs and test points for this process and are discussed.  The various methods built into this process to measure the map accuracy of the ortho image produced are reviewed. A sample exercise is provided using a color IKONOS 4-meter resolution image of La Jolla Mesa, San Diego County, California and the corresponding DEM that will fit within the practice limits of TNTlite.

Revised Tutorials with Major Changes.

The following tutorial booklets have been revised since the release of RV6.9.  They were selected for update since they represent areas of significant recent changes in the TNT products. The added functionality of newly released features is introduced by the addition of new pages and examples as noted.  As part of this update, their user interface illustrations, terminology, default parameters, and sample data have also been adjusted to be current with RV7.0 of the TNT products. 

Managing Relational Databases has been updated to include shape objects and changes to tabular view.  The illustrations were updated throughout the booklet and terminology was adjusted to reflect the current interface and defaults.  The following new pages were added.

• Changing Related Only to Directly Linked—how to use directly attached tables to make related only tables into directly attached tables so a database can be simplified;

• Database Validate and Attachment Types—introduces database validation and discusses the importance and implications of various attachment types;

• Link to ODBC Data Sources—presents the Link to Data Sources feature in Display and contrasts it with linking during import; and

• Many Ways to Associate Tables—summarizes the many ways to associate database information with objects in the TNT products.

Printing has been updated to include color management and newly supported external formats.   The following new pages were added.

• Color Management—color profiles (ICM and ICC) and how to proof to the screen;

• Printing to External Formats—converting layouts to TIFF, Adobe Illustrator (*.ai), PDF, EPS, and SVG;

• Options When Printing to SVG—compression and layer controls; and

• Hints for Reliable Printing—setting printer defaults and page orientation, do not dither twice, printing transparency efficiently.

Vector Analysis Operations has been updated to include material on creating and using grids with accompanying exercises.  The following new pages were added.

• Grid Analysis—generating grids within reference objects;

• Grids for Extraction—using generated grids to extract from raster objects;

• Grids and Surface Properties—getting surface properties for generated grid polygons; and

• Vectors and Surfaces—converting 2D vectors to 3D vectors and using 3D view in editing.

Glossary for Geospatial Science has many new terms added, such as “conflation,” resulting in an increase from 64 to 72 pages.

Floating License Setup and Management Guide has been completely updated, expanded, and tested.

Quick Guides.

Quick Guides outline the operation of a small selection of TNT features in a very concise form or provide quick reference sheets for things like Hot Keys.  They are created in response to user input and support questions that indicate clients are unaware or overlooking specific shortcuts or key features of the TNT products.  As a result they are not a comprehensive collection, which would require thousands of pages in this Quick Guide format, but only intended to address these special concerns.  All previously existing Quick Guides have been revised and updated to be current with RV7.0.

Available Online.

All 58 currently available Quick Guides are now installed in PDF format from your CD with your RV7.0 TNT product.  You can access these Guides online using Display / Quick Guides or Help / Quick Guides.  This feature is illustrated on the accompanying color plate entitled Quick Guides Available from Menu.  A single search in Abobe Reader will now cover the contents of these Guides as well as the tutorial booklets and the reference manual.  

This searching is also now available for the first time in the Mac OS X versions of the TNT products.  To use this feature you will need to designate that Abobe Reader is your default application for viewing PDF files.  Apple wishes you to stay within its own software so Apple Preview is the default for PDF files and the Adobe search indexes are ignored.  The same color plate discusses this and how you can switch your default application to Adobe Reader to use these TNT searches.   

New Quick Guides.

The following new Quick Guides are provided in printed form as part of your RV7.0 upgrade kit.  Some synopsize new features added to RV7.0 and some cover previous features of which you may be unaware.   These and all the other upgraded Quick Guides are installed in PDF from the CD as part of RV7.0 or can be downloaded from www.microimages.com/didyouknow/.

Editor’s Right Mouse Button Menu.

Set up a custom right mouse button menu for quick access to a variety of frequently used editing functions.

Database Prompt in the Spatial Data Editor.

Choose to be automatically prompted to enter attributes when elements are added or divided while editing.

Designing Database Forms.

Create a form from a table for data entry and viewing that includes the fields and added labels of your choice.

Cosmetic Database Constraints & Forms.

Change the field prefix to include spaces and symbols not allowed in field names and add text after a field.

Operational Database Constraints.

Place constraints on fields to control how they are filled out during data entry operations.

Adding Frames to Labels.

Include frames for use with labels and leader lines for automatic (on-the-fly) labels.

Automatic Labels and Leader Lines. (new feature in RV7.0)

Control label position and the use of leader lines for automatic (on-the-fly) polygon labels.

Cross Sections with Style. (improved feature in RV7.0)

Generate a cross section with drawing styles that match the original vector object.

RVC Object Validation. (new feature in RV7.0)

Check your RVC files and objects for validity and conflicts using Project File Maintenance.

Copying Objects.

Copy files and most object types to a new location using Project File Maintenance.

Zooming to Full Resolution (1X). (new feature in RV7.0)

Choose any raster layer in a group or layout to provide the scale for a full resolution (1X) zoom.

Extract and Trim DRGs.

Select the Digital Raster Graphics (DRG) of a scanned map directly in its TIFF format and automatically extract it to trim off the collar information.

Toggling Map Grid Tick Mark Colors.

Toggle between two colors for interior map grid ticks.

Using Special Characters.

Visually select and insert special characters from the fonts character map window without typing the character’s code.

New TNTmips Features 

Main or subsections preceded by the asterisk “*” symbol introduce significant new processes or features in existing processes released for the first time in TNTmips RV7.0.  You will find more sections marked in this fashion than usual in this MEMO.  This results from the incorporation into this release of the results of several longer term background recoding and development projects—some stretching over several years.

System Level Changes.

Project Files.

CAD Objects.

Text elements (in other words, strings) stored in a CAD object can now be assigned styling and be displayed with similar appearance properties to those available for vector objects in V6.9.  CAD text elements can now also be multi-lined.  Each text element can have distinct label frames and use one or more leader lines.  Text element alignment can use multi-point label baselines with straight, exact, and spline fits of the text to the baseline.  A sample application of these new features of CAD objects will be discussed in more detail in the section below entitled Sketching.

Raster Objects.

Pyramids.  A global option is available Support / Setup / Preferences on the Project File tabbed panel to require that all TNT processes compute full binary pyramids.  Computing full binary pyramids is the defaualt.  You can turn on a toggle to skip the 2 by 2 pyramid, which will decrease the raster size by 25% and speed up its creation.  However, having the full set of pyramids will improve the detail and speed up the display of this raster for you as your zooming approaches 1 to 1.

JPEG2000 Objects.  Raster objects can now be greater than 4 GB when compressed with JPEG2000.  This will be a common result when mosaicking many orthophoto raster objects into a single JPEG2000 compressed raster object.  However, to use this new capability, your operating system must be new enough to permit any file, thus a Project File containing this compressed raster object, to exceed 4 GB and your hard drive must be formatted appropriately.  Drive formats that will permit files, thus Project Files, to exceed 4 GB are:

• Windows NT, 2000, XP, 2003:  NTFS;

• Mac OS X (all versions):   HFS or HFS Extended;

• Linux (for various flavors):  ext2, ext3, ReiserFS, XFS, and JFS; and

• Unix: any current format used.

JPEG Objects.  Auto-linking to directly display and use JPEG format files (*.jpg) is now supported.  If georeference information is provided it will be used automatically from the companion files with the same name but with the *.jgw (world file) extension.

PNG Objects.  Auto-linking to directly display and use PNG format files (*.png) is now supported.  If an ICM color profile or gamma/chromaticity values exist, the link to the PNG file will bring it in as an ICM color profile subobject in the TNT link file.  If an alpha channel exists in the PNG file, an opacity mask raster object will be created in the TNT link file.  A color plate entitled Directly Use PNG Files accompanies this MEMO to illustrate and further discuss features provided by this new linked format.

Vector Objects.

Validating topology in vector objects in RV7.0 is now faster.  Considerable effort has been expended to optimize computations in the steps used on the graphical elements in a vector object during validation.  More information on this topic can be found in the major section below entitled Validating Vector Topology. Reconciliation of the contents of complex relational database structures is still time consuming and will be the focus of future optimization in the validation engine.  

Georeference Subobjects.

The georeference subobject is now updated to handle more verbose georeference information.  A new georeference type called manifold is now supported in the georeference subobject.  The georeference subobject has been expanded to handle control point names and IDs, whether control points are enabled or disabled, linking two control points together to define a hard edge and linking multiple control points to define a boundary for use in piecewise models, and support for the new Coordinate Reference System (CRS).  If the georeference subobject does not contain any of the above features and the CRS can be represented in the georeference subobject format of TNTmips 6.9 and earlier, the georeference subobject will be usable in earlier versions of the TNT products.

Maintenance.

Object Size Information.  The Object Information dialog in Project File Maintenance now reports the amount of Project File space a geodata object uses and has a separate entry for the total amount of Project File space for the object and all of the subobjects of that geodata object.  

Object Warnings.  The hierarchical structure of your geodata is tested whenever a primary object is being copied or the Project File is being packed.  Yes, it would be appropriate if every TNT process and activity was designed to prevent violations from being created for that object type and this is an area for continued effort.  However, violations can occur when data uses older processes, is manipulated by you outside the TNT products (for example, via SML or TNTsdk), or errors occur.  If a violation is detected, a dialog will appear to inform you of the problem(s) and what the operation being used will or will not do about it.

The Object Information dialog in Project File Maintenance now also highlights subobjects in its subobject list that violate the allowed hierarchy structure for that primary geodata object type.  Normally all information in this dialog is in black text.  Text information about a subobject presented in the color Red indicates that this subobject is not valid under the parent object for which it is listed.  Magenta text is used as a warning that the subobject is of the same type as another subobject under the same parent and that only one is needed and will be used.  Blue text is used as a warning to indicate that the object or subobject has links to some other, possibly external objects or files, and that they cannot be found.  The colors are used in a hierarchy at the file level such that if any objects or subobjects would be shown in red, the file is shown in red but may also contain objects or subobjects that are shown in magenta or blue.

Vector Object Standard Properties.  The Edit Object Information dialog accessible from the Edit icon button in Project File Maintenance for vector objects now provides another means to optionally enable or disable the maintenance of standard attribute and element ID tables.  Remember that if you choose to enable these properties to be continuously maintained, this will slow down processes, such as editing a vector object, which then must continuously correct and maintain these tables.  As an alternative at any time you can create these standard property tables by using Process/Vector/Attributes/ Standard Attributes.

* Validating Vector Topology. 

Conflation, what is it?

The Random House Unabridged Dictionary defines conflate as “to fuse into one entity, to merge.”  From conflate comes the word conflation that is defined as “the process or result of fusing items into one entity; fusion; amalgamation.”  This is probably a new word in your vocabulary, but is used by the technologists in the GIS community in reference to maintaining topology. 

Conflation is a major objective of the TNT vector validate process, to merge line elements that should be the same into a single element in order to maintain correct topology.  Incorrect conflation, thus incomplete validation, yields “conflation errors,” which means that topological errors have been created.  It is not appropriate to refer to these as validation errors in that the validate process does many other things besides merging graphical elements.  Often conflation errors take the form of long triangles of microscopic width that are so small as to be practically invisible and might be called “no seeums” or invisible.  This example of a conflation error can not readily be detected or filtered out using the TNT polygon area filter as it’s difficult to detect and its area can not be readily computed due to limitations in the floating point computations involved.

Conflation errors are usually only a very few in number and if they go unresolved and undetected, they may or may not effect some future application with the vector object.  For example, if a single, microscopic triangle is created, it may never be a source of difficulty unless by chance in some future merge with another object, a new line happens to bisect it.  When this happens, the error in the process being used, such as merging vectors, is difficult to find since it resulted from an undetected condition created somewhere else in the input vector objects.  

Conflation errors do not necessarily originate in some vector object process within the TNT products.  The import of a carelessly prepared or very large CAD or shapefile subsequently used to create a vector object can create a conflation error. It is MicroImages’ responsibility to insure that conflation errors do not occur and are detected and resolved by the validate process when they do.  Alas, as your vector object size increases, the probability of the conditions occurring that could create a conflation error also increases.  Since you are now using much larger, national level or locally high detail vector objects, the probability of geometric conditions existing that create a conflation error have increased.  Thus you must now be made aware of this concept, how it comes about, and the considerable software effort invested in RV7.0 to insure that these errors are detected and resolved every time a vector object is validated.

How do you “catch it”?  

A common maxim is that “one person’s signal is another’s noise.”  You must pay close attention to the disposition of the small features created by combining input objects of any type into a polygonal topology vector object.  It may be obvious that you are combining graphical elements when you use TNT procedures like Combine and Merge.  It may not be as obvious that this is also happening when you perform an Import, Copy then Paste, or use the new Extract process to merge several objects of varying types.

Probably the most common source of conflation problems are those that occur during the import of a very large non-topological dataset(s), particularly from ArcView shapefiles, AutoCAD DXF, and other CAD formats.  Single shapefiles are being imported into TNTmips that are 1 to 2 gigabytes in size.  A lot of complex data might have been overlaid into one of these files with the intention that it would only be used for displaying it as graphics from the CAD or shapefile.  Importing these kinds of files into a vector object with polygonal topology may cause conflation errors to occur.  

Another way to increase the probability of encountering conflation errors is to make duplicate versions of a vector object containing numerous polygons.  Using these identical vector objects as templates, you then subject each separately to a variety of changes, such as editing or merging, that creates many, many new polygons.  These result in tiny but rare changes in the vertices of the original polygons due to round off changes in their coordinates.  Later, if these vector objects are recombined, these polygons are no longer absolutely identical and in some geometric combinations result in microscopic conflation errors.  

Is it a problem?

The small topological graphical features that result from conflation when a vector object is validated can be divided into two groups.  Artifacts: those small features that you decide are indeed artifacts for your purposes and must subsequently be removed from the vector object by the polygon area filter.  Artifacts can be easily seen if you zoom into your object many times (for example, 10 times, not 10X).  Conflation Errors: microscopic differences in the features that should have been treated as identical but do not conflate and yield new error features, primarily due to the limitations imposed by the mathematical precision of the process.   Often these microscopic features appear due to round-off errors in the floating point computations on double precision coordinates of previously identical vertices.  They would still occur even if greater floating point and coordinate precision were used.  They would just be even smaller as they constitute computation noise.  Eliminating or preventing the possible subsequent negative effects of these tiny conflation errors hiding in a vector object is the responsibility of MicroImages since we created them. 

Can it be avoided?  

Many new small triangles and polygons are almost always added when overlapping geometric objects are combined into a new vector object.  These may be noise in your application and can be deleted from the new vector object using a small polygon filter.  Or, they may be significant new small agricultural plots or movements in the edges of ecotones (transition edges of ecological communities) with an area of a few thousand square meters in a vector object covering an entire province or nation.  Another common effect of combining objects is creation of slightly different 2 point features that might result from meaningless displacements in duplicated survey or GPS differences.  Conversely these same small displacements can be quite important in a study of the land subsidence or movement using repeatedly measured polygon boundaries.

Understanding what topology is and that it is maintained at a considerable cost in computation time can help you use procedures that reduce the creation of artifacts and conflation errors.  For example, you snap to a line between two nodes by any means, such as extending the line or crossing and intersecting it.  No matter the mathematical precision used in the computation, the new 3^rd node will not be perfectly on the old line at the numbered limits.  This is no particular problem in that vector object.  However, the original line is duplicated in a second vector object.  If the 2 objects are combined the original line and the 2 new lines form a microscopic triangle.  No problem as this is easily detected in validate.  But it gets harder to do if the original straight line is very long because the acute angles of the triangle get smaller and smaller.  No problem here as yet either.  But this original line exists in 6 more vector objects since it started in all as a national or provincial reference boundary.  All of these have other edit activities performed separately on them and the same original line gets nodes snapped to it at other intermediate positions. Still not a problem—until all 8 objects are combined at one time.  Now the geometry for this area gets very complicated with even more microscopic triangles being formed, and in special circumstances it is difficult to resolve the conflation error that results.  If you think through this example, you can also understand that if the layers were combined two at a time this error would have a significantly lower probability of occurrence.  For example combine object 1 and 2 to get object Z and validate.  Next combine object 3 and Z and validate, and so on until object 8 is combined with the previous result.  This approach would not take any longer in computer time to do.  Furthermore, the order of combining the pairs can also be changed to avoid errors.

Duplicating a vector and then editing the various copies can be convenient. It is important that polygons in all objects be bounded by the same political, project, or physical boundaries. For example, you have provincial boundaries in a vector object and create several duplicates of them in new vector objects to be used as a base for the collection of other graphical features.  Subsequently combining these objects may result in an error in conflation that is not resolved in the validation and is detected and reported.  When this happens, it is the responsibility of MicroImages to resolve this complex geometry during validation.  However, we must have your vector objects to reproduce the complex geometry leading to the error and thus resolve errors of that type in future combination operations.   

Can you see it? 

Conflation error features are so small that you would have to zoom in to a view scale approaching zero to see them even if you know where to look.  This might be 20 zoom in operations beyond where a “0” scale first appears as the TNT view scale.  A zoom scale showing as “0” means that you are asymptotically approaching close to zero (for example, an actual scale of .01).  For example, when you have zoomed in enough to see a conflation error triangle (perhaps a scale of .0001) and use the measurement tool to measure the smallest side of the triangle, you might find that it is a less than a millimeter and even approaching microns on the ground in a vector object with an extent of 1000 kilometers.   

What is the effect of the cure?

Creating and continuously maintaining topology is a unique property of the TNT vector objects.  It is maintained in various processes by the TNT validation procedure.  Significant effort has been expended in RV7.0 in improvements in this validate procedure for testing for, detecting, and resolving hidden conflation errors.  These low-level, “under-the-hood” changes to validate will not be directly visible to you, but will make subsequent uses of your vector objects, such as their combination, more reliable especially with large vector objects. Detecting conflation errors and repairing them for large vector combination operations does require a lot of CPU time.  To offset these new demands for CPU time, the previously routine validation operations have many new optimizations.   Thus, you will notice that although validate is doing a lot more work in RV7.0, it is faster than V6.9 when dealing with common vector object operations requiring validation.

Alas, these continuing improvements in validate and its speed are offset by your insatiable desire to create and work with larger and larger vector objects.  Using larger vector objects comes at a price.  As their size increases, they can slow down validate in a non-linear manner, especially when there is a requirement to reconcile very complex, attached relational database structures.  Speeding up this activity in validate will be an improvement that you can expect in DV7.1.  Increasing size also exacerbates the situation by introducing more conflation errors into your operations that combine vector objects.  Also importing bigger shapefiles, DXF, and similar graphical files increases the probability that they contain pseudo-duplicated data structures such as crisscrossing overlapping polygons, which create artifacts and conflation errors. 

Where are the current capabilities? 

Recently you brought to our attention several problems with large vector objects that occurred during their combination or subsequent uses.  These were eventually traced to a few conflation errors.  A single undetected conflation error creates difficulties and perhaps halts validation in a later step.  Fortunately two clients were able to provide MicroImages with complete datasets that exhibited these problems.  These both have provided the basis for extensive effort software development and testing to pinpoint the errors and add code to detect them and then to fix them.  Discussing these 2 test cases will help you become familiar with these microscopic but important topological issues.

Large Shapefile Import to a Vector Object.
One test case was a large shapefile containing contours that was obtained by the client from the Internet for import into a vector object.  Its size was ~1.4 GB and contained 61,543,650 vertices defining 1,849,392 lines connected by 1,965,573 nodes and 1 table.  Since this shapefile had no polygons, they were formed in validate and you might assume that it had no intersections.  However, it contained retraced line segments that did initially create microscopic conflation errors during the validation portion of its import into a vector object.       

Merging Nation-Sized Vector Objects.
This test case involved the combination in the merge operation of 8 vector objects covering an entire medium-sized nation.  The makeup of these vector objects was as follows:

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