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Additional Textures

fermigas edited this page Oct 14, 2018 · 3 revisions

Description

More texture files.

Note: the texture files mentioned on this page are used to display Digital Elevation Models in grayscale form. They are not intended, and cannot be used, for generating digital simulations of the Moon. For that purpose, you need to follow the directions for Obtaining DEM data.

Kaguya Global Topography

The following image (click to retrieve at full size), is a map of lunar surface elevations based on Kaguya laser altimeter measurements. The data have 16 points per degree, and have been linearly scaled here so that the full height range covers the 0 to 255 unit span of a grayscale JPEG image. Light colored points are high, and dark ones are low.

external image LALT_GGT_MAP.jpg?size=64 (click this and other thumbnails for full-sized image)

The image is in simple cylindrical projection running from -180° to +180° from left to right, and +90° to -90° from top to bottom. Hence it can be used as a standard texture in LTVT.

The grayscale range of 256 units corresponds to a height of -9.14 km relative to the 1737.4 km reference sphere (black), to +10.72 km (white), in a linear fashion.

Digital height data of this sort can be used for creating two- or three-dimensional computer simulations of the Moon as viewed and lit from an arbitrary direction. Unfortunately the 256 levels possible in a JPEG image give a vertical resolution of 19.86/256 = 78 meters, which is not quite adequate to represent some of the subtler slopes: over a distance of 1/16th degree (1.89 km), this could produce a slope as great as 2.4°, which would significantly affect shadow rendering. As a result, height "images" with greater bit depth are normally used for that purpose. See the Digital Topography page for more details.

High and Low Points

Here is a labeled LTVT screenshot centered on the location of the highest point in the Kaguya global DEM (marked by a red plus mark) on the shared rim of the craters Engel'gardt and Engel'gardt B:
external image Kaguya_LALT_HighestPointOnMoon.jpg?size=64 (click thumbnail to see full-sized screenshot)

And the lowest point (marked by a light blue plus mark), on the floor of an unnamed crater inside Antoniadi:
external image Kaguya_LALT_LowestPointOnMoon.jpg?size=64 (click thumbnail to see full-sized screenshot)

Note that the IAU feature positions are systematically displaced from where the features appear in the DEM. This is a problem with the IAU database and not with the Kaguya DEM, which appears to be accurately registered. If you choose to use the Kaguya Global Texture, until the IAU positions are corrected, these screenshots can be used to verify that it is displaying correctly.

Polar Topography

Since Kaguya passed over the Moon's poles on each orbit, the laser altimeter made more measurements in those areas, and more densely spaced height data for the areas within 10° of the poles have been released. The spacing in latitude is 64 points per degree, four times higher than for the global DEM. As with the global DEM, the data have here been reduced, in a linear fashion, to the scale of intensities from 0..255 that can be represented in a JPEG texture.

North Pole

This image, in simple cylindrical projection, runs from +90° in latitude (at top) to +80° in latitude (at bottom), and from -180° in longitude (at left) to +180° in longitude (at right). The grayscale corresponds to the reported range of elevations from -4.988 km (black) to +2.300 km (white). It can be used as Texture 3 in generating LTVT displays.

The image is too wide to generate an automatic thumbnail, but you can click here to retrieve the north polar texture file at full size.

South Pole

This image, in simple cylindrical projection, runs from -80° in latitude (at top) to -90° in latitude (at bottom), and from -180° in longitude (at left) to +180° in longitude (at right). The grayscale corresponds to the reported range of elevations from -4.988 km (black) to +2.300 km (white). It can be used as Texture 3 in generating LTVT displays.

The image is too wide to generate an automatic thumbnail, but you can click here to retrieve the north polar texture file at full size.

LOLA Global Topography

Here is the 16 points per degree LDEM_16.IMG from 16 Mar 2010 of LOLA data transformed to a JPEG grayscale image, which can be used as an LTVT texture. The intensities of "0" and "256" corresponding to the extremes of the altitude range given in the DEM info. The map has been adjusted so that it spans the LTVT default range -180° to +180° in longitude and +90° to -90° in latitude (the original spans 0° to 360° in longitude, which, in LTVT, can be used only as "Texture 3"):

  • external image LOLA_LDEM_16.jpg?size=64 (click thumbnail to see full-sized image)

The 64 points per degree LDEM_64.IMG from 16 Mar 2010, is also available as a 256-level grayscale texture, although it is too wide to generate a thumbnail. Right-click here and select "Save target as..." or "Save link as..." to download a copy (6.7 MB). The details of the LDEM_64.IMG from which it was derived can be found in the DEM info. The grayscale version has been adjusted to span the LTVT default longitude range of -180° to +180°.

LROC Global Textures

French amateur Jean-Charles Bouget has assembled LTVT-compatible global lunar texture files from several Lunar Reconnaissance Orbiter Camera datasets. Although they are too large to upload to the LTVT Wiki, Jean-Charles has kindly made them available on his Dropbox site.


This page has been edited 10 times. The last modification was made by - JimMosher JimMosher on May 22, 2016 6:00 pm

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