Space Shuttle Endeavor Data and Lake Levels

Space Shuttle Endeavor Data
Written By Michael Ulrych
(How I used it to set lake levels)

STS-99 Mission: Shuttle Radar Topography Mission, Space Shuttle: Endeavour,

Launched: February 11, 2000, 12:43:40 p.m. EST Landing: February 22, 2000, 6:22:23 p.m. EDT

STS-99 Commander Kevin R. Kregel, Pilot Dominic L. Pudwill Gorie, Mission Specialists Janet L. Kavandi, Janice E. Voss, Mamoru Mohri and Gerhard P. J. Thiele.

In February 2000, Space Shuttle Endeavor went on a mission to map a large portion of the earth’s geography. The mission was named SRTM or Shuttle Radar Topography Mission. The idea was to measure the earth’s surface with two radars on board Endeavor. One radar was located in the shuttle cargo bay and the other at the end of a 200 ft mast projecting out from the cargo bay. The mission was a success. You can read more about it here.

The data collected originally went to NASA’s Jet Propulsion Laboratory; now it resides on a USGS server in South Dakota where public access is granted. In order to create the terrains you see in the Lahontan images, I use this data, and am happy to give NASA, USGS, the Shuttle crew and everyone involved, much thanks and credit.

My process is as follows. I select the earthly terrain of interest and download a DEM (Digital Elevation Map) file from the USGS server in South Dakota. I import this file into rendering software and do some adjustments to stretch the terrain very carefully so as not to change any proportions. At this point, I have a blank terrain covered with a default texture. If you were familiar with the area downloaded, you would see the outline of a recognizable hill and mountain features seen outside. It looks like this:

An example of what blank terrain looks like from a digital elevation map. Note: this is a 3-D space that the camera can enter and spin around inside of.

The task now is to cover the terrain any way you like using the rendering tools.

My desire was to set a water level from a non-existent lake back into the terrain at the highest level it had attained.  For that lake level, I used several geology papers, particularly Kenneth D. Adams and Steven G. Wesnousky’s paper entitled Shoreline Processes and the Age of the Lake Lahontan Highstand in the Jessup Embayment. The paper was kindly furnished to me by Dr. Adams.

For the Ancient Lake Lahontan images, I strived for accuracy, so establishing the water level of the ancient lake was critical to see what those places looked like before the lake dried up.  Let me explain how I set the lake levels into these mountain terrains.  Each DEM (Digital Elevation Map) file is accompanied with meta data about that particular terrain.  Included in the data is the highest and lowest elevations of the mountains within that terrain.  Know that in a 3-dimensional scene, each element within the scene has an X, Y and Z axis.  I simply assign the DEM file elevations into my render.   By using the Ancient Lake Lahontan highstand data from geologists, it is easy to place the water level exactly where it needs to go relative to the landscape.

NOTE: These renders do not take into account a phenomena referred to as isostatic rebound. For those of us who are not geologists, understand that Ancient Lake Lahontan was a huge lake with millions of tons of water weight pushing down into the crust of the earth. This massive weight strained and deformed the surrounding shoreline hillsides. This explains why when the water was removed, the crust rebounded causing uneven shorelines, (literally shorelines with drifting elevations) around the perimeter of the valley.

With the terrain in the render thanks to STS-99 and the lake level set thanks to local geologists, now comes the artistic element. I relied on many numerous sources to guide my effort to cover the area with vegetation and fluvial features. Donald K. Greyson’s textbook entitled The Great Basin is a wonderful work and fascinating read; it helped me greatly. I always intended these images to be pleasant to look at as well as scientifically accurate. So the task of coloring the hillsides, deciding where to put the sun along its arc, choosing the color of water, and the types of clouds in the air was entirely artistic.

The final product is what I believe to be a beautiful rendition of Ancient Lake Lahontan, thousands of years ago in photographic quality!