Finding Magellan Radar Images at the PDS Sites
Each month, the PRPDC features one component of the Planetary Data System (PDS). Here we focus on the Magellan radar data set, which is presented by the USGS PDS Imaging Node and the Geosciences PDS Node at Washington University. Together, they enable you to access the full resolution (F-Map) Magellan radar backscatter images. Image #1 shows our entry point to determine which image you need, using Flagstaff's Map a Planet web site.
You can go to this site here: click here, or continue with our tutorial.
The first thing to do is to look at the global map of Venus, which is shown in Image #1. You will need to zoom in on the part of the planet you are interested in and by holding the cursor over the map find the latitude and longitude of you selected image. This is shown in Image #2.
Image #1: Screen shot of the Map a Planet Venus page
Image #2: (1) How to zoom into a particular part of the global map, and (2) where to look for the latitude and longitude of your study area.
Once you have written down the latitude and longitude, you will have to switch web sites, as it is the University of Washington at St. Louis that has the full-resolution data. You can go to this site here: click here, or continue with our tutorial. If you continue on this page, you may well want to print it out, as we go from one web page to another!
Image #3: Screen shot of the list of Magellan mosaicked image data records
When you are at Image #3, you will have to (1) scroll down the various latitude/longitude combinations (alas, they are not in order) and then (2) look for the relevant MG number for the file you want.
Once you have written down the MG number (e.g., MG_0001), you will have to go to another page to select the full-resolution data. You can go to this page here: click here, or continue with our tutorial.
Go to Image #4 to see what to do next.
Image #4. Here you will see a list of all the Magellan data set volumes. Click on the volume that you need (i.e., the one you found using Image #3). Click on this "mg" number, and you will be taken to a page that looks like Image #5.
Image #5: Screen shot of the list of the full resolution Magellan directories in this volume. Again, search for the relevant latitude and longitude that you need, and click on the relevant file, as this will take you to another page (shown in Image #6).
Image #6: Screen shot of the contents of this directory. So that you know what the entire scene looks like, you need to inspect the "browse image". What you do now depends upon the software that you have on your computer. Alas, the browse images are not in .jpeg format. Instead, they are .img files. If you have Correl software, you can click on the browse image. This will take you to the low-resolution image, which is shown in Image #8. If you do not have this software, click on the file called "lbl". This shows which files to download (using the right click "save function" on your mouse). The two files to download are called "browse.img" and "browse.lbl", as shown in Image #7.
Image #7: Screen shot of the label information for the specific full resolution image that you are looking for. You will need to write down two numbers, which are the "Record Bytes" (the number of lines in the image) and the "File Records" (the number of columns in the image).
Image #8: Screen shot of the browse version of the Magellan image. We have superimposed a grid on this image, because you will see in Image #6 that there are many "ff" images, which are the full resolution subscenes. These "ff" images are numbered so that they first run across the top of the scene, then start a second row, etc. Pick the number you see here and then go back to Image #6 to click on the relevant files.
When you click on the "ff" number (Image #6) you will then get to see the full resolution image that you want. An example, using the ENVI software, is shown in Image #9.
Image #9: This is what we are looking for -- a full resolution Magellan image! Here we display the data using the ENVI software, so that you have a scroll image, a full-resolution sub-scene, and a zoomed-in part of the full-resolution data.
Now that you have discovered how you can access all of the full resolution Magellan images, you can click here to go straight to USGS Flagstaff Map a Planet' PDS site to get your own data.