Blending Terragen 2 with GIS Data

Concept for this Terragen 2 Tutorial

One of the greatest benefits of this Terragen 2 tutorial is that you will be able to quickly and easily import and use real world data and information in any of your renders. There is a great deal of data available for free download on the internet, but it can be fairly confusing to both find what you need and then figure out what it is you have. I will try and make sense of a few basic ideas and you can take it from there. Some knowledge about geographic information systems would be of benefit, but should not be totally necessary.

Software used

This is the software that I will be using in this Terragen 2 tutorial, but there are plenty other options that would work as well. You would likely be able to exchange GlobalMapper for a free GIS package and Photoshop for The Gimp and do any of the same conversions.

Data

For this Terragen 2 tutorial I will be using Canadian GIS data from British Columbia mainly because I know that the data is fairly high quality and I am familiar with both the locations and formats of the data. There is plenty of other GIS data available online at varying detail levels that you may be able to apply these same principals to.

DEM (Digital Elevation Model) Data

This can be downloaded free of charge from the following website: www.geobase.ca

Finding the correct data blocks can be somewhat tricky depending on how much mapping knowledge you have, but for ease of reference, Canada is broken up in sections based on the National Topographic Survey system. Basically there will be 3 different scales of data (1:1,000,000 – 1:250,000 – 1:50,000.) For the purpose of this tutorial we will be using the best resolution 1:50,000 scale data available.

You can find an index of Canada maps here: http://www.geobase.ca/geobase/en/browse.do?produit=cded&decoupage=50k&map=canada

For this tutorial we will be working with six 1:50,000 scale maps covering the area around Whistler, British Columbia (Location of the 2010 Olympic Winter Games).

The maps we will be using are designated: 092G10, 092G11, 092G14, 092G15, 092J02, 092J03

Canadian Topographic Maps

These files will be mostly for reference and orienting yourself once the data has been imported into Terragen 2.

You can download these files at the following website: http://ftp2.cits.rncan.gc.ca/pub/canmatrix/

If you are following along with the Terragen 2 tutorial, here are the direct links to the files I am using:

Canadian Landsat 7 Satellite Data

These files will be important for building higher resolution masks of detailed features of your landscape.

You can download these files at the following website: http://ftp2.cits.rncan.gc.ca/pub/canimage/

If you are following along with the Terragen 2 tutorial, here are the direct links to the files I am using:

Canadian Vector Data

This data is made up of dozens of vector data layers containing everything from roadways, contour lines, building, elevation points, vegetation areas, wetlands, rivers, lakes, and many more features that you would find on a traditional map. We will use these layers to easily mask out large areas of our landscape.

You can download these files at the following website: http://ftp2.cits.rncan.gc.ca/pub/canvec/

If you are following along with the Terragen 2 tutorial, here are the direct links to the files I am using:

Assemble the Data

Now that you have all this data downloaded it is time to do something with it. First of all you should start by opening the six DEM files in Global Mapper. Once the data is open I would suggest reprojecting the data to be in a UTM format (for these files it will be UTM Zone 10, North American Datum 83 (NAD83). You can do this by selecting “Tools > Configure” then selecting the projection tab and changing the projection from Geographic to UTM.

You should see on your screen a nice representation of what your landscape will look like.

You will then export the data as a terragen .ter file. I personally use either 4097 X 4097 or 8193 X 8193. When exporting it is best if you use a square box to pick the area that you want coverage for.

Next you should open the six topographic map files. You will notice that the maps all have large borders on them that you will have to turn off. If you open the control centre and select all six maps, you can then choose the option to “Automatically crop DRG style collar” which will give you a seamless map area.

You will then export this using the exact same boundary area as you exported your terrain.

Follow the same steps for the satellite images.

You now have a terrain, a topographic reference map, and a satellite image reference map. Next we will create some layers based on vector data.

You will need to unzip the CanVec data into a new folder as there will be a few hundred files. An overly complicated reference guide for the canvec layer specifications can be found here: http://ftp2.cits.rncan.gc.ca/pub/canvec/doc/CanVec_feature_catalogue_v1_0_1_en.pdf

Or you can use my simple chart to pick the layers you want to work with: CanVec Reference Chart

For this tutorial we will only be concerned with Glaciers, Vegetation, Rivers and Lakes.

Unload all the previous data from GlobalMapper, but do not close the program (we don’t want to lose the previous export boundaries).

Now load in the Vegetation shape file layers. They can be identified by the following characteristic:

  • VE_1240009 – There should be six files to load in, one for each map file.

Once these are open, you will need to select the type of feature for each layer. I have selected that they should be filled by solid black. Now export this layer using the same boundary as the previous exports.

Unload all the data again and import the Permanent snow layers. They can be identified by the following characteristic:

  • HD_1140009 – Permanent Glacial Ice

Then change each file to be filled with solid black as before and export this layer too.

Unload all the data again and import the river and lakes layers. They can be identified by the following characteristic:

  • HD_1150009 – Coastal Water
  • HD_1470009 – Single Line Waterbody
  • HD_1480009 – Waterbody

Once again change each file to be filled with solid black and export this layer as well.

Now that all our data is converted and gathered it is time to start getting it imported into Terragen 2.

Importing and Working with the Data

Before we import anything into Terragen 2 we are going to need to know exactly how large (in meters) the terrain we are importing is. For me the easiest way to get this information is to first import the .ter file into Terragen 0.9x and then click on the ‘Size” button. There will be two numbers (they will be exactly the same if you exported a square terrain size) that are of critical importance. For my export these were 64359.58 x 64359.58. What this will let you do is appropriately scale your image masks to the exact size of the .ter file you imported.

Finally open Terragen 2 and begin by loading the .ter hightfield by either using the menu or by adding the nodes on your own. I will assume some level of knowledge when it comes to adding the appropriate nodes.

The shader you want for this is a “Heightfield Load” Once the .ter has been imported, under the heightfield shader dialog, change the position from “position lower left” to “position centre”. This is not technically needed but it makes more sense to me.

You will most likely need to reposition the camera as chances are pretty good that you will be far below the surface of the terrain.

Next step is figuring out where you are in terms of real life features and this is where the topographic and satellite map data is useful.

Create an image map shader and load the topographic map image you exported. Change the projection type to “Plan Y” choose “Position Centre” and enter the size of your .ter file (the number you obtained from TG 0.9x) into the size fields. Then give it an appropriate name and do the exact same thing for the satellite image. Typically once I have these loaded I create an “Overlay” group just to keep things organized, but that is purely cosmetic.

Now it is possible to quickly switch back and forth from your normal texture, to either the satellite image map or the topographic image map, just by attaching either image map as your last shader before the planet object.

Topographic Overlay Node Network and Sample Image




Satellite Overlay Node Network and Sample Image




With these two overlays you should be able to quickly and easily move around your area and find the features that you are interested in. Once you have an area in mind we can start masking out actual features.

To create our masks of various features (Vegetation areas, Permanent Glaciers, and Lakes and Rivers) we will need three more image map shaders. Each one will be set up the same as we did previously with the projection set as “Plan Y”, “Position Centre”, and the size set to the size in metres of your .ter file. For each of the masks load a different layer. For this tutorial that would be a vegetation area layer, permanent glacier layer, and lakes and rivers layer.

Once again I create a separate group for these nodes just to keep things organized.

You can now go ahead and use these masks to set up whatever sort of typical shaders you normally use. Here is an example of just a very simple setup with a few surface layers.

The only thing to be aware of is that using the masks I set up, because the feature coverage in the images is set to black, you will need to check the “invert blendshader” box.

Here is the current node network for this project:

Final Comments

Now that you have the basic idea for using the data, the only limitations are your imagination and creativity for building a realistic scene. Some ideas could be to create higher resolution tree masks using aerial photography or better satellite data to accurately map out where the avalanche runs are; building up an accurate road or railway network; adding ski slopes or even importing buildings for the towns.

Using these simple ideas I was able to fairly quickly put together the following render (click on the image for the full size version):

Terragen 2 tutorial result

If you made it through all of that I hope that you take away a little bit more understanding about how to use various sources of data to improve your Terragen 2 renders

If you are unable to create the .ter files and masks yourself you can download my project files here:

You can download a .pdf version of this tutorial by using the link below:

Any comments, suggestions or problems can be sent to:

Ryan Archer
r.archer@shaw.ca

archer-designs.com