VTP FAQ

About the Project

  1. If the VTP is a software project, why is there so much information about other tools and technologies on this website?
  2. Who maintains the VTP website, and writes the software?

General Questions

  1. Can i run the VTP Software on my own computer?
  2. Does it run on Linux?
  3. Does it run on Mac OS X?
  4. What is the license the VTP source code?  Is it under the GPL?
  5. Where is the documentation?
  6. Is there a tutorial?
  7. How can i capture screen output from the VTP (AVI/MPEG movies)?
  8. What is a heixel?
  9. Does the VTP any image limit..? I would like to work with a better resolution, but I found some problems with large images..?
  10. How is the VTP software different from Google Earth?

Troubleshooting

  1. What is the Windows XP error message:  "This application has failed to start.."
  2. What is IPL.DLL?
  3. Why can't i load my BT elevation files in Enviro.  The status bar has a message starting with "The elevation data is of an unsupported size..." and nothing appears.
  4. Why are some of the geospecific textures not a power of 2 in size?  For example, bigisland_ls_2045.jpg
  5. I'm loading a 3D model from a 3DS file.  The model looks solid white in Enviro, why?
  6. Why does Enviro run so slow?  I'm getting only 2-3 frames per second.
  7. I found LULC data and loaded it loaded up OK in VTBuilder. When I try to save the vegetation layer to the Plant data (*.vf) nothing happens.
  8. VTBuilder crashes when i try to import data from an SDTS file.
  9. On Windows, some files cannot be opened, if the path name contains international characters, like "F:\数据\file.tif"

Feature Requests

  1. Have you implemented the hydrology layer in Enviro?  There are no Rivers, or water folder.
  2. I'd like to make some vehicles, like cars, drive around on the terrain.
  3. There are some other features I'd like to see.

About the Project

  1. Q: If the VTP is a specific software project, why is there so much information about other tools and technologies on this website?
    A: The VTP's goal is to advance the entire field of terrain visualization.  That's why the site tracks every related subject and software package.  Producing and supporting the VTP's own software is only part of the larger goal.
  2. Q: Who maintains the website, and writes the software?
    A: The project manager and lead developer is Ben Discoe (email / old personal site).  There have been additional developers working on the underlying libraries, doing the Linux and MacOSX port, and improving the applications.  There are also data and website contributions from the VTP user community.  There is a mailing list for support and discussion.

General Questions

  1. Q: Can i run the VTP Software on my own computer?
    A:     Yes.  Download the software, which includes ready-to-run programs, data, and the complete C++ source code.

  2. Q: Does it run on Linux?
    A: Yes.  If you are a developer, you can build the software on just about any unix flavor (Linux, Irix,  FreeBSD, Mac OS X...) in addition to Microsoft Windows.

  3. Q: Does it run on Mac OS X?
    A: It does build and run natively (if you are a skilled Mac developer), but there are no prebuilt binaries, yet.  Reportedly, the VTP software for Windows does run well in emulation on the Mac, in particular with VMWare Fusion or Parallels Desktop.

  4. Q: What is the license on the VTP source code?  Is it under the GPL?
    A: There are no restrictions.  It is not under the GPL, but instead under a more flexible license which is basically the MIT/X license.  You do not even have to disclose the source if you improve it or include it in products that you sell.

  5. Q: Where is the documentation?
    A:     If you installed from the Windows Installer, there are already links to the documentation on your Start Menu.  If you installed the binaries manually, there is a "Docs" folder under each application.  Also, all the documentation is online.
  6. Q: Is there a tutorial?
    A:     There are some simple tutorials in the documentation.  It is recommend to start with the first tutorial.  However, there are hundreds of ways of using the VTP software, depending on what kind of data you have.  To cover them all would take hundreds of tutorials, because there is no "common" case.
    Consult the website about the kind of data you're working with, to learn about it, then read the VTP docs for each application, starting with VTBuilder.  There is also the mailing list to ask questions and get help.
  7. Q: How can i capture screen output from the VTP (AVI/MPEG movies)?
    A: Enviro has a snapshot feature for still images.  For more sophisticated capture including movies, there are numerous apps available such as Camtasia Studio, or perhaps an open-source alternative such as TAKSI.  For best results, try to capture the video output externally (with a DVR or second computer) so that the computer does not have to attempt 3D rendering and video capture at the same time.  Alternately, you can use Enviro's Play animation to disk command in the Locations dialog, then encode the frames with your choice of software.
  8. Q: What's a heixel?
    A:     A heixel is a heightfield element - similar to how a "pixel" is a picture element, "voxel" is a volumetric element, and "texel" is a texture element.  Other ways to refer to a heixel are "elevation grid sample point" or "height of elevation raster at a given coordinate" - but consider that heixel is a much shorter and simpler term.
  9. Q: Has VTP any image limit..? I would like to work with a better resolution, but I found some problems with large images..?
    A:     Yes.  With a single texture, the limit is your graphics card.  However, as of 2006, you can now use VTBuilder to produce image tilesets which allow for any amount of imagery (and elevation) which is smoothly paged at runtime.
  10. Q: How is the VTP software different from Google Earth?
    A:     The VTP is an open platform for any kind of terrain visualization.  The list of what distinguishes VTP over GE is very long, here is a small sample: supports coordinate system projections, dynamic procedural culture including buildings, fences/walls/pipelines, vegetation that is species-aware, bathymetry, direct loading of 3D models from every file format, time of day lighting/shading, accurate sun location, simulation elements including vehicles, procedural texture-mapped roads, support for every geodata format including every USGS format, direct visualization of GIS layers, 100% open and extensible, can be used by commercial users, fully documented API…
    What distinguishes GE over VTP is: it provides free, limited (view-only) access to a huge, seamless database of (public) elevation and (proprietary) imagery.  For more about GE, see the online review.

Troubleshooting

  1. Q: On Windows XP, i get this error:
        "This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix this problem."
    A:     Blame Microsoft for this bad message.  It has been seen on some computers, generally with older .NET installed.  There is no good reason for it, because VTP does not use .NET, at all.  To fix, you should install the VC 2008 SP1 Redistributable Package.
  2. Q: What is IPL.DLL? It was not part of the download and BExtractor needs it to run. Where do i get it?
    A:     Look at the BExtractor documentation before trying to run it.  Consider whether you in fact have USGS DRGs with the need to do auto-extraction of building locations.  If you aren't using USGS DRGs, you don't need BExtractor.
  3. Q: I have been unable to load my BT elevation files in Enviro.  The status bar has a message starting with "The elevation data is of an unsupported size..." and nothing appears.
    A:     To use the dynamic LOD, your BT must be a square power-of-2-plus-1.  For example. 1025*1025 or 2049*2049.  It's convenient to use VTBuilder's "Merge and Resample Elevation" feature which will do this for you.
  4. Q: Why are some of the geospecific textures not a power of 2 in size?  For example, bigisland_ls_2045.jpg
    A:     Those are for 4x4 Tiled texturing, see overlapping tile approach.  Don't try to use them as single textures.  In the parameters dialog, you just give Enviro the tile size and prefix, and it generates the filename.
  5. Q: I'm loading a 3D model from a 3DS file.  The model looks solid white in Enviro, why?
    A:     Make sure that your 3DS file has materials defined for it.  If there are no materials, it will appear solid white.  Keep in mind that the "ambient" and "diffuse" components of each material should add up to the fully illuminated color that you want to see.
  6. Q: Why does Enviro run so slow?  I'm getting only 2-3 frames per second.
    A:     Your OpenGL may not be accelerated.  Start Enviro and press the "OpenGL Info" button.  If it says "Renderer: GDI Generic" then you are not hardware accelerated.  Consult the support for your 3D card, e.g. install the latest drivers.
    Another cause of this problem can be low memory.  Try closing any other large applications you have running, then try again.
  7. Q: I found LULC data and loaded it loaded up OK in VTBuilder. When I try to save the vegetation layer to the Plant data (*.vf) nothing happens.
    A: .vf     is for actual vegetation (a set of plant instances), whereas LULC and SHP Vegetation Layers only describe potential vegetation.
  8. Q: VTBuilder crashes when i try to import data from an SDTS file.
    A:     If you used the popular program WinZip, you may have corrupted the file.  See the SDTS Warning Page under "Decompression Software" for how to avoid this problem.
  9. Q: On Windows, some files cannot be opened, if the path name contains international characters, like "F:\数据\file.tif"
    A:     This is a limitation of some the component libraries inside the VTP (primarily, GDAL and OSG) which do not accept Unicode (or UTF-8) filenames.  The VTP software itself completely supports Unicode and internationalization.  The component libraries have been notified of the problem and solution, but to date they have not been fixed.

Feature Requests

  1. Q: Have you implemented the hydrology layer in Enviro?  There are no Rivers, or water folder.
    A:     Not yet.  In fact, Water Layers in VTBuilder are only raw data, and cannot be saved.  The reason for this is that there is not yet a good way to render water bodies on the terrain.  When someone implements that, then it will become useful to save water layers.
  2. Q: I'd like to make some vehicles, like cars, drive around on the terrain.
    A:      The short answer is that there is currently no way to do this without programming.  If you can write C++, then it is possible to add this capability using vtlib.  In fact, since vtlib used to have vehicle support, much of the work is already done.
  3. Q: There are some other features I'd like to see.
    A: Check the list of feature requests to see if it's already there.  If it isn't, you could ask for it on the mailing list.  Also, if you are a C++ programmer, feel free to just go ahead and implement it yourself, this is one great thing about Open Source!

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