Over the past few days, I've been digging up information on NASA FTPs. But, why?...
^ That's why. Our project is going to, if possible, use actual NASA terrain and elevation data to produce landscape models for Venus and Mars. Right now, the only really decent data I've got is for Mars via the MOLA satellite - the above image is from the lowest resolution available, where the data is interpreted by a free program from the NASA Planetary Data System. This program is called NASAview.
The problem at hand now is that I need to determine how to get elevation data, which a greyscale image doesn't readily show - instead, any image from Mars via the data is dynamic - the program will automatically adjust the shade of any selected region's max, min, and mean elevation data and spit out that information within 255 (254, technically) shades of grey. This is great, because for the most part we'll use these maps to generate 3D terrain from the greyscale image... but we still need to know the maximum and minimum altitudes of the region in question for this to work.
Fortunately, despite all of those silly politicians cutting education and the space program (you know, actually important things?), NASA is still made of win, so much so that they'll answer my questions about how to use the available data:
The MOLA PEDR data set (Precision Experiment Data Record) is the source of the elevation values shown in the MOLA topographic maps. The PEDR data are not images but binary tables containing the along-track altimetry measurements recorded by the MOLA instrument. The data are online here:
These data files are in a custom binary format which is rather complicated. You would have to write special software to read them. An example of such software is given in the SOFTWARE directory of the archive.
Many users prefer not to tackle the daunting job of reading, interpreting, and mapping the altimetry measurements. A tool is available that will do this work for you. It is the MOLA Query Tool, part of our Mars Orbital Data Explorer (Mars ODE) service. ODE is primarily a service for selecting and downloading Mars orbital data from many instruments, but for MOLA in particular a special function is provided in response to the great interest from our users in this data set. With the MOLA Query Tool you may select from the data base of altimetry measurements by latitude, longitude, altitude, time, orbit, or product ID. Results can be returned in the form of ASCII tables, CSV tables, shapefiles, or binned images.
The ODE home page is here: http://ode.rsl.wustl.edu/mars. Look for "MOLA PEDR Query" under "Additional Tools". If you have questions about using this tool for your particular project, the best person to ask is ODE developer Keith Bennett, [email protected].
So, yes. this is entirely doable. The next issue, which unfortunately is more pressing... is Venus. The information from our last Venus mission, Magellan, is also available. Magellan's information, unfortunately, is early 90's vintage, and it shows. I've got a bit more research to do before I can put together precisely what I need to do or how I need to do it, but it will get there. Assumably, that might involve some more emails with technical questions, but ones does what they must.
Regardless, feel free to ask any questions if you have any. The NASA PDS data is freely available to the public, so if you think something would be of use to a project you're working on, have a look! However, you'll most certainly want to konw what you're looking for. And if you find it, be prepared to do the research to make use of the information you obtain. Again, I'll be happy to share any information I've learned so far.