This latter format is provided for software that doesn't work well with either floating-point or signed integer files. For the unsigned 16-bit TIFFs, the source data was offset by +20,000 (10 km) so that all of the values are positive. For the floating-point TIFFs, the source data was divided by 2000. LOLA's gridded elevation data is published as signed 16-bit integers in units of half-meters relative to this radius. The reference surface for all LRO data is a sphere of radius 1737.4 km. A small subset of the LOLA data stored there, the global cylindrical projections at 4, 16, and 64 pixels per degree, has been reformatted here as uncompressed TIFF files, in vertical units of either floating-point kilometers or 16-bit unsigned integer half-meters. LOLA data is archived on the Geosciences Node of the Planetary Data System. The displacement map (also known as a height map or elevation map) was taken directly from the latest (as of spring 2019) gridded data products of the Lunar Orbiter Laser Altimeter instrument team. Scientific applications should use the source data. This image is optimized for aesthetics, not science. When rendered with realistic shadows, these parts of the map aren't particularly visible, and while they comprise more than 20% of the map's pixels, they represent only 6% of the Moon's surface. For this color map, the missing latitudes were filled in with a combination of monochromatic LROC data and an albedo map ( LDAM) from LRO's laser altimeter. Because the Moon's axial and orbital tilts are both small, many areas outside these latitudes remain shrouded in shadow, even after thousands of passes by LRO's camera, so they are left out of the LROC mosaic. The source data covers the lunar globe from 70°N to 70°S. Small data dropouts near the top and bottom were inpainted using Photoshop's content-aware spot healing brush.
The intensity range (0.16, 0.4) was mapped into the full (0, 255) 8-bit range per channel.
A gamma of 2.8 was applied (the LROC data is linear), and the channels were multiplied by (0.935, 1.005, 1.04) to balance the color. The red channel contains the 643 nm band, while green and blue were created from different linear combinations of the 566 and 415 nm bands to more nearly center them on 532 nm (green) and 472 nm (blue). A less formal introduction to the process is in this LROC blog post and in this one.įor the color map here, the visualizer modified and combined three of the seven wavelength bands of the LROC color data to more closely match what the human eye sees. The readme file provides a technical summary of how the mosaic was constructed along with references to more detailed publications. The color map was adapted from the Hapke Normalized WAC Mosaic, a composite built by the camera team from over 100,000 WAC (Wide Angle Camera) images.