Importing Data into
originally written by Andy Johnson (aej at evl.uic.edu) in Feb 2003 and modified in spring 2004
Part 1 - Getting data from other applications ready for walkabout
that is, how to create a model landscape and a seet of geo-referenced texture maps.
Right now there are instructions here for Global Mapper and Microdem.
MicroDEM to Walkabout
Thanks to Peter Guth this is pretty easy - Microdem will even create the .wbt file for you! You will need at least version 8.0alpha (build 126.96.36.199) for this to work.
- load in your favourite data set of the terrain with your favourite image into MicroDEM
- click on the green house in the menu bar (it has the tooltip VRML 3D Viewer)
- outline the part of the landscape that you want to visualize by clicking and dragging a box from the northwest corner to the southeast corner.
- in the VRML viewing options box click on the Walkabout radio button and then you can give a name to the set of files you will generate. If you stick with the default then any previous files you have saved with this name will be overwritten - this is useful if you just want to quickly walk over the landscape. If you want to save this set of files you should probably give it a more descriptive name. Then click OK
- if this is the first time you are doing this you will be asked for the location of your walkabout executable. Its usually in C:Program Files\GeoWall Consortium\Walkabout\Walkabout.exe
- walkabout will automatically launch with your current settings for stereo mode and window size. If you want to change those default settings you can use the walkabout front end.
- the landscape you are viewing is called test.wrl with DRAPE-MAP.JPG overlayed on it. These two files, along with test.wbt, are created in a directory named as you specified above in MicroDEM's mapdata\vrml directory. The landscape test.wrl is a .wrl file so it can't be optimized by walkabout, however you can convert it to an .iv file using the walkabout front end and that .iv file can be optimized by walkabout usually giving twice the speed. To do this optimization you can start up the front end and use the convert menu.
Global Mapper to Walkabout
- load in your favourite data set of the terrain
- pick your favourite shading method for the image to overlay on the terrain
- in the file menu select Export Raster and Elevation Data
first choose Export VRML...
- Under the VRML Options tab pick the Resolution you want and be sure to uncheck the 'Generate Compressed WRZ file' box. We dont want the VRML file to be compressed. Under the Export Bounds tab pick and the subset of the data you want and then click OK to save off myScene.wrl
then chose Export JPG...
- Under the General Options tab pick the Sample Spacing you want. Under the Export Bounds pick the same subset of the data you chose for the VRML file and then save off myScene.jpg
Also under the Export Bounds tab you should note down what the Global Projection (UTM - meters) North, South, East, and West bounds are since you will need to tell walkabout what these are. I'm not sure if there is a convenient way to get the minimum and maximum elevations. I just moved my mouse around the main Global Mapper window to likely high and low points and wrote down the numbers that appeared at the bottom right of the screen. :)
Now you have two files. The jpeg file is ready to go. The wrl file needs a little work. The front end for walkabout has a convert menu where you can select a .wrl file like the one you generated above and generate the appropriate .iv file. Walkabout also comes with a command line version called 3dem2iv in case you need to convert a bunch of file from the command line with a command such as "3dem2ivOSX myScene.wrl" to generate myScene.iv. I think or most people the menu option in the front end should be sufficient.
Elevation GeoTiff to Walkabout
This is still pretty experimental but the front end for walkabout has a new menu option to convert elevation GeoTiffs into both a .iv file for the landscape and a .wbt file containing the necessary scene parameters. This process also tries to scale down the landscape to a size that should be walkable at a good frame rate
- Use the convert menu in the front end to choose your .tif file. At this point walkabout will generate the correcponding .iv file and .wbt file with the same basic filename. By default the landscape will have a maximum size of 1200x1200 but you can change this size using the Convert menu to "Set Maximum Size of Landscape Converted from .tif"
- Use the front end to load the .wbt file. By default the landscape will be there scaled according to the coordinates given in the GeoTiff. Without a texture its hard to see what the landscape looks like. As a temporary fix the .wbt file will try to load the default.jpg texture. This texture can be found in the main walkabout directory, so you can copy default.jpg to the directory with the .tif, .wbt and .iv file, or even better generate your own textures that go along with the geotiff and use the front end to add them into the .wbt file.
seamless.usgs.gov to Walkabout
This also seems pretty straightforward, though I have only tested a few types of data. I have downloaded 1/3" NED as a GeoTiff tiff and Hi-Res OrthoImagery and 1 meter resolution Orthoimagery as tiff files. You need to press the "Modify Data Requirements" at the seamless site to get to the options to change the NED format from ArcGrid to Tiff. I also set the WGS84 Coordinate Display to Decimal degrees. The Hi-Res OrthoImagery actually has far too much detail for walkabout to use as a texture, while the NED seems a bit low resolution.
Once you have the various files you can run the NED GeoTiff through the walkabout front end elevation GeoTiff converter to get a .iv file and a .wbt file. You will also want to convert the orthoimagery tiff into a .jpg file that is either 1024x1024 or 2048x2048 or 4096x4096 depending on the quality of your videocard. You should be able to do that conversion with a program such as Adobe Photoshop or Graphic Converter, etc.
Then you can load the new<whatever>.TIF.wbt scene file into the walkabout front end, remove the default.jpg texture, add in your new <whatever_else>.jpg texture and start walking. If you download multiple textures you can add them all in here and slip between them while walking.
Mars to Walkabout
If you get bored walking on the Earth you can also use walkabout to walk on Mars, though the procedure isn't as simple as the previous ones.
If you have other georeferenced jpeg files you can use them as well in walkabout as long as North is to the top and East is to the right on the screen.
There are some things to note about textures however. Since Walkabout is written in OpenGL, OpenGL prefers to have textures whose sides have lengths that are powers of two - eg 256 or 512 or 1024 or 2048 or 4096 on a side. If you give walkabout a texture with a side length that is not a power of two then OpenGL will scale it to the next higher power of two automatically but that just wastes space, so its better if you can generate textures that have side lengths that are powers of two.
It should also be noted that different graphics cards have different limits on the sizes of the textuers themselves. Pretty much all modern cards can handle 1024 x 1024. Many can handle 2048 x 2048. There are a few that can handle 4096 x 4096. If you give a texture that is too big for the card the card will scale down the texture, so you should generate textures at a size that is appropriate for your current graphics card.
Now you can go on to part 2 of the tutorial below which describes how to use the walkabout front end to create and set various parameters of the landscape's .wbt file. If you used MicroDEM to create your landscape then you already have a .wbt file called test.wbt.
Part 2: Using the walkabout front end to set various parameters of the landscape
Walkabout uses a scene file to encapsulate all of the data on a given visualization.
This scene file includes information such as:
There are two ways to create a scene file. You can use a text editor or a word processor to create the file by hand, or you can use the front-end to walkabout to create and modify scene files. This file will concentrate on using the front-end.
At this point, if you do not have a copy of walkabout, then you should get one:
The latest stable version (updated roughly once a month) can be found at ftp://ftp.evl.uic.edu/pub/software/andy/WALKABOUT.tar.gz
The latest beta version (updated several times per week) can be found at ftp://ftp.evl.uic.edu/pub/INcoming/andy/WALKABOUT.tar.gz
For information on installing walkabout you can see the readme file enclosed in the distribution.
Starting the front end
On the Macintosh you can double-click on the front icon: or start front from the command line.
On Windows you can either double-click on the front icon or select walkabout from the Start menu.
On Linux you don't have a spiffy looking icon yet to double-click on, so you can double-click on the boring generic application icon or start front from the command line.
Creating a New Scene File
The walkabout distribution comes with the Hickey data set (including a correct scene file), so we will use that as an example in what comes below.
When front is running you will see a screen like this:
Before you go through this tutorial you should have already gotten walkabout set up and viewed the sample Hickey dataset as described in the walkabout README html file. This means you should have already set your screen size to something like 1024x750, and chosen a user name to identify yourself to others on the network. You should have the arrangement set to either display monoscopically on your monitor/LCD panel, or one of the stereo options for the GeoWall. You should have located your version of the walkabout executable. Finally you should have saved these settings using the "Save as Defaults" button.
To create a new scene file, you should click on the "Add/New Scene" button in the lower left corner. This will bring up a file chooser. We are going to go into the HICKEY directory that is distributed with Walkabout. On Windows by default this directory can be found in C:/Program Files/GeoWall Consortium/Walkabout. On OS-X and Linux it should be in the same directory as front. If you need to change drives you can use the "Favorites" button in the file chooser.Once you have found the HICKEY directory, you will see a list of files like the one shown below. We are going to create a new scene file in this directory called Scene.new.wbt, so you can type Scene.new.wbt at the end of the path given in the Filename box at the bottom of the file chooser, and then press the OK button. All scene files are given the extension .wbt.
At this point you are taken back to the main screen in front, and you can click on this new scene file. When you do that you will see the following dialogue box pop up telling you that front is setting up this new file with the default visualization values.
When you press the OK button you will see a series of tabs on the right side for the various settings. By default you start with the User tab. You probably don't need to change any of these right now.
Clicking on the "Scene" tab brings up the view below. Eventually you will use this tab to set the UTM values for the corners of the landscape as well as the minimum and maximum elevation. For now we will stick with the default values. We will also leave the starting point blank, since by default you will start in the center of the landscape.
Clicking on the "Landscapes" tab brings up the view below. Currently there are no landscapes, so we will add one by clicking on the "Add Landscape" button.
Now you see another file chooser which will allow you to select files of type .iv, inventor files. The only inventor file in the HICKEY directory is hickey_geomap.iv so click on that file to select it and then click on OK. The file chooser will also allow you to chose .wrl (VRML-2) files. Some .wrl files will work and some will not. It is best if you can convert these files to .iv format using the Convert menu since then walkabout can optimize them and walking/flying over them will be a smoother experience.
Now you can see that the hickey_geomap.iv landscape has been added. Unfortunately the hickey .iv file was created in Bryce so is not oriented correctly. We need to rotate this file 180 degrees about the vertical (Z) axis for it to line up with the texture map, and get north aligned correctly. So you should click on hickey_geomap.iv to select it, and then the three rotation boxes will appear to the right. Select the Rot Z box and type 180 into it. Depending on how the landscape was created, different rotations will be needed.
For landscapes created in Global Mapper or MicroDEM, the landscape will not need to be rotated.
Clicking on the "Textures" tab brings up the view below. Currently there are no textures, so we will add one by clicking on the "Add Texture" button.
Now you see another file chooser which will allow you to select files of type .jpg, jpeg files. The only jpeg file in the HICKEY directory is Terrain2_diffcol.jpg so click on that file to select it and then click on OK.
Now you can see that the Terrain2_diffcol.jpg texture has been added.
That is all you need to do to right now. So click on the "Save Scene" button to save the contents of the scene file. If you want to save the current list of scene files so they are available when you restart front, you can use the "Save as Defaults" button.
Now to view this new scene file you can click on the "view scene" file to view it. This view will look similar to hickey scene file except here the landscape is smaller and the mountains seem higher because we are using the default sizes rather than those that are correct for hickey - this is why you start out staring into a mountainside as shown below on the left, but if you back up you can see the view on the right.
If you want to share a walkabout session with another user then you can click on the "Network" tab. Here you can list the IP address (or addresses) of the other computers running walkabout, or another computer running a walkabout reflector. You should probably stick to the default values for the other parameters for now.
last update June 22, 2004.