LRO LOLA Gridded Data Record Counts (GDRDEC)
GDRDEC – Gridded Data Record Counts
Instrument: Lunar Orbiter Laser Altimeter
PDS Data Set ID: LRO-L-LOLA-4-GDR-V1.0DOI: 10.17189/1520642
PDS4 Bundle:urn:nasa:pds:lro_lola_rdrDOI: 10.17189/tnyt-7007
LRO PDS3 to PDS4 Migration Status: Complete
For more information about LOLA calibrated and derived products, see the RDR Product SIS.
For more information about the LOLA PDS3 volume, see the LOLA Archive Volume SIS.
The Lunar Orbiter Laser Altimeter (LOLA) Gridded Data Records (GDRDEC) data products are map-projected digital elevation counts (samples per pixel) used to generate the digital elevation models (GDRDEM) products. Each product uses data acquired through various mission phases. The GDRDEC data products contain the binned, interpolated altimetric measurements on a uniformly-spaced grid.
A pixel in the GDRDEC 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.
The resolution of equirectangular pixels is in powers of two pixels per degree of longitude and latitude (e.g. 4, 16, 64, 128, 256, 512, and 1024). The resolution of polar projected pixels is in integral numbers of meters at a radius of 1,737,400 m, true at the pole. The pole is a point surrounded by the four central pixels, and the colatitude of a pixel at a distance r meters from the north pole is simply 2arctan(0.5r/1,737,400). Polar stereographic projections are produced at latitudes from 45 degrees to the poles.
Equirectangular map-projected digital elevation counts
|
Product |
Pixel size (latitude) |
Number/size of tiles |
Bits per pixel |
|
LDEC_4 |
7.5808 km |
Global, 0-360 |
16 |
|
LDEC_16 |
1.895 km |
Global, 0-360 |
16 |
|
LDEC_64 |
0.4738 km |
Global, 0-360 |
16 |
|
LDEC_128 |
0.2369 km |
Global, 0-360 |
16 |
|
LDEC_256 |
118.45 m |
4 tiles, longitudes 0:180:360 by N/S |
16 |
|
LDEC_512 |
59.225 m |
Longitudes 0:90:180:270:360 by 45° latitude bands |
16 |
|
LDEC_1024 |
29.612 m |
Longitudes 0:45:90:135:180:225:270:315:360 by 22.5° latitude bands |
16 |
Selection of polar map-projected digital elevation counts, N/S
|
Product |
Dimensions |
Pixel size |
Latitude range |
Bits per pixel |
|
LDEC_45S_100M |
28880 x 28800 |
100 x 100 m |
+/- 45° to pole |
16 |
|
LDEC_60S_60M |
31040 x 31040 |
60 x 60 m |
+/- 60° to pole |
16 |
|
LDEC_75S_30M |
30496 x 30496 |
30 x 30 m |
+/- 75° to pole |
16 |
|
LDEC_80S_20M |
30400 x 30400 |
20 x 20 m |
+/- 80° to pole |
16 |
|
LDEC_85S_10M |
30336 x 30336 |
10 x 10 m |
+/- 85° to pole |
16 |
|
LDEC_87S_5M |
30336 x 30336 |
5 x 5 m |
+/- 87.5° to pole |
16 |
LOLA GDRDEC global 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
LOLA GDRDEC regional products have the following file names:
product_mmmd_nnnd_www_eeesuffix
where:
product = product name above
mmm = minimum tile latitude in degrees
d = direction of minimum latitude
N = north
S = south
nnn = maximum tile latitude in degrees
d = direction of maximum latitude
N = north
S = south
www = westernmost longitude in degrees
eee = easternmost longitude in degrees
suffix = file type/extension
.IMG = image file
.LBL = detached PDS label
.JP2 = JPEG2000 file
_JP2.LBL = detached PDS label
In ODE, GDRDEC products have one of the following product IDs:
PRODUCT
PRODUCT_IMG (polar image files only)