Mars km-scale roughness maps

 

Here you can browse and download roughness maps of Mars derived from the final version of entire MOLA data set. The papers and images referenced within this page are large and we recommend downloading them to disk (as opposed to loading them in a browser window). PC users should right click and Save to Disk. Mac users should hold down their mouse button until they get the pop-up window and then Download Link to Disk or Alt + Click on the desired link.

The maps are calculated in a way described in [Kreslavsky and Head 2000] (pdf) with minor modifications.

See also [Kreslavsky and Head 2002] (pdf), [Kreslavsky and Head 1999] (pdf) and technical information.

These papers should be referenced when using the data.

The map scale is 8 pixels per degree.

 

E8R.TIF Roughness map of the whole planet in simple cylindrical projection

 

N8R.TIF Roughness map of the Northern hemisphere in Lambert azimuthal polar equal-area projection

 

S8R.TIF Roughness map of the Southern hemisphere in Lambert azimuthal polar equal-area projection

 

The maps are presented as RGB composite images stored in TIFF format.

The Blue, Green and Red channels contain roughness at 0.6 km, 2.4 km, and 9.2 km baselines.

Brighter shades denote rougher surface. Thus, general brightness denotes general roughness, and color hue denotes the nature of the scale dependence of roughness. See [Kreslavsky and Head 2000] (pdf) for further details.

 

DN values in channels are stretched for the best visual presentation of the whole maps. This stretch is the same for all map projections.

Not stretched data suitable for qualitative analysis can be downloaded below (see also technical information):

 

Roughness data files

 

 

Projection

 

 

0.6 km baseline

 

 

2.4 km baseline

 

 

9.2 km baseline

 

 

Simple cylindrical projection

 

 

E8R0.RAW

 

 

E8R1.RAW

 

 

E8R2.RAW

 

 

Lambert azimuthal polar equal-area projection - North

 

N8R0.RAW

 

 

N8R1.RAW

 

 

N8R2.RAW

 

 

Lambert azimuthal polar equal-area projection - South

 

S8R0.RAW

 

 

S8R1.RAW

 

 

S8R2.RAW

 

 

 

Projections.

 

Simple cylindrical projection.

2880 x 1440 pixels.

If the uppermost leftmost pixel has coordinates x = 1, y = 1, then

north latitude (deg) = (720.5 - x) / 8

east longitude (deg) = (y + 0.5) / 8

 

Lambert azimuthal polar equal-area projection for the Northern hemisphere

1440 x 1440 pixels.

If the uppermost leftmost pixel has coordinates x = 1, y = 1, then

r2 = (x - 720.5)2+ (y - 720.5)2

north latitude (deg) = -2 asin( p r / 2880) + 90, where asin should be taken in degrees

east longitude (deg) = atan2(x - 720.5, y - 720.5), where atan2 should be taken in degrees

 

Lambert azimuthal polar equal-area projection for the Southern hemisphere

1440 x 1440 pixels.

If the uppermost leftmost pixel has coordinates x = 1, y = 1, then

r2 = (x - 720.5)2+ (y - 720.5)2

south latitude (deg) = -2 asin( p r / 2880) + 90, where asin should be taken in degrees

east longitude (deg) = atan2(x - 720.5, 720.5 - y), where atan2 should be taken in degrees

 

Technical information

 

Roughness was calculated with the following procedure.

Good MOLA shots from nadir-looking orbits were selected.

For each given MOLA shot, profile curvature was calculated as:

c = ( h+ + h- - 2h) / (4l2),

where h, h+, and h- are MOLA-measured surface elevations from the given shot, a shot half-a-baseline ahead and a shot half-a-baseline behind along the orbit; l is the baseline length.
The baselines used correspond to 2, 8, and 32 shot-to-shot distances.

All calculated curvature values were binned in the map cells.

The interquatrile width C of the curvature-frequency distribution was used as a measure of roughness for each map cell.

 

Data files are simple data arrays without any labels and headers, one byte per pixel, arranged line by line from the top to the bottom of the map. Roughness C is called to the pixel value DN by the following logarithmic equation:

 

DN = 80 log10(C l) + 511

 

Further technical questions should be addressed to

M. Kreslavsky misha@mare.geo.brown.edu