Telescope Reviews: Altai Scarp

Timo,

You may be interested to know that you can use this "LOPAM" texture in LTVT as well. Under "Files...Change external file associations..." simply click on any of the three textures and browse to the folder "C:\Program Files\VirtualMoon\Database\Textures\" folder (or wherever you have VMA installed) and select "hires_lopam.jpg" (or any other texture file you like, such as "moon_full_geology.jpg"). Any file that covers the whole Moon in "simple cylindrical projection" from -180° (left) to +180° (right) in longitude and +90° (top) to -90° (bottom) in latitude can be selected and will display properly.

Even better, you can order (for free) many other texture files from the new Map-a-Planet. Simply use the Advanced Options to request a Simple Cylindrical projection (in JPG format) with the margins set as above and whatever pixels per degree you think your computer memory can handle. In this way you should be able to download a version of the Lunar Orbiter texture of considerably higher resolution than the one provided with VMA, allowing you to "zoom" in much tighter. You can see the ultimate resolution of the LO survey photos on the Map-a-Planet site, but to cover the entire Moon in that detail may take more megabytes than your computer's memory can cope with at a single time. Also, if the file size you request is more than a few megabytes you will have to follow the "shopping cart" directions: in a day or two they will send you a URL from which you can retrieve your file.

I haven't had a chance to verify this personally in any detail, but a neat thing about the new USGS Lunar Orbiter composite is that it's supposed to be the first global map of the Moon showing all features in their selenodetically correct locations. So you are supposed to be able to read coordinates and distances off it with confidence. This is not true of most versions of the Clementine basemap and Shaded Relief maps. Features on those are often seriously misplaced. Presumably the corrected Clementine and Shaded Relief maps that have been recently prepared by the USGS will also eventually become available for free download via Map-a-Planet (I don't think they're there yet).

Incidentally, I'm not sure the authors recommend this, but it's also possible to trick VMA into displaying alternate textures. In the folder mentioned above, you simply insert the new simple cylindrical maps you want to use and re-name them to the names expected by VMA ("hires.jpg" for the Shaded Relief, "hisres_clem.jpg" for Clementine, and "hires_lopam.jpg") -- after being careful to backup the original ones. At least this used to work. You may also have to manually erase (or rename) the *.dat files to encourage VMA to re-generate its sections from the new textures. Unfortunately, no matter how high resolution the texture is, you can't really take advantage of the added detail because you can't force VMA beyond its intrinsic zoom limit.

-- Jim