# LRO LOLA Gridded Data Record Roughness Map (GDRDRM)

### GDRDRM – Gridded Data Record Roughness Map

**Instrument:** Lunar Orbiter Laser Altimeter

**PDS Data Set ID:** LRO-L-LOLA-4-GDR-V1.0

For more information about LOLA RDR and derived products, see the RDR Product SIS.

For more information about all LOLA products, see the LOLA Archive Volume SIS.

The Lunar Orbiter Laser Altimeter (LOLA) Gridded Data Record Roughness Mass (GDRDRM) data product is a map of surface roughness for the Moon, based on altimetry data acquired by the LOLA instrument. The residual standard deviation of altitudes from three successive laser shots with n-3 degrees of freedom after fitting a plane to n=5 to 15 profile returns, is averaged in each pixel. Depending on orbital velocity, probability of detection, and spacecraft altitude, the slope baseline may vary from 30 to 120 meters.

The surface roughness value is scaled:

Roughness = DN * SCALING_FACTOR. (DN = Digital Number)

A pixel in the GDRDRM product represents the mean value at the center of a region bounded by lines of constant longitude and latitude at integral numbers of degrees or fractions thereof, scaled and interpolated where necessary. The size of the products at higher resolutions requires that they be aggregated in subsets of global coverage. Global standard products use the Equirectangular map projection, also known as Simple Cylindrical, while the higher-resolution products afforded by dense polar coverage use the Polar Stereographic projection.

### Equirectangular map-projected roughness maps

Product |
Pixel size (latitude) |
Number/size of tiles |
Bits per pixel |

LDRM_16 |
1.8952 km |
Global, 0-360 |
16 |

### Polar map-projected roughness maps, N/S

Product |
Dimensions |
Pixel size |
Latitude range |
Bits per pixel |

LDRM_75S_240M |
3812 x 3812 |
240 x 240 m |
+/- 75° to pole |
16 |

LDRM_85S_40M |
7584 x 7584 |
40 x 40 m |
+/- 85° to pole |
16 |

### LOLA GDRDRM products have the following file names:

productsuffix

where:

product = product name above

suffix = file type/extension

.IMG = image file

.LBL = detached PDS label

.JP2 = JPEG2000 file

_JP2.LBL = detached PDS label

### In ODE, GDRDRM products have the following product IDs:

PRODUCT