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There
are several map projections commonly used in Texas. In an
effort to maintain some sanity, we have restricted our data
holdings to three: UTM - NAD83 for high resolution data, Texas
State Mapping System (TSMS) for statewide data, and Geographic
for national datasets such as US Census data and ESRI US and
World datasets. The following charts give the parameters for
these common projections:
| Texas State Mapping
System |
| Use |
Seamless, statewide
data |
| Projection |
Lambert Conformal
Conic |
| Spheroid |
GRS 80 |
| Datum |
North American Datum
of 1983 (NAD83) |
| Longitude of
Origin |
100° West (-100) |
| Latitude of Origin |
31° 10’
North (31.16) |
| 1st Std Parallel |
27° 25’
North (27.416) |
| 2nd Std Parallel |
34° 55’
North (34.916) |
| False Easting |
1,000,000 meters |
| False Northing |
1,000,000 meters |
| Units |
Meters |
| Universal Transverse
Mercator (UTM) |
| Use |
High-resolution
(1:24,000) data sets |
| Projection |
Transverse Mercator |
| Spheroid |
GCS North American
1983 |
| Datum |
North American Datum
of 1983 (NAD83) |
| Central Meridian |
Zone 15: 93°;
Zone 14: 99°; Zone 13:105° |
| Latitude of Origin |
0° North |
| False Easting |
500,000 meters |
| False Northing |
0 meters |
| Units |
Meters |
| Geographic |
| Use |
National datasets |
| Projection |
Geographic Coordinates
(unprojected) |
| Spheroid |
GCS North American
1983 |
| Datum |
North American Datum
of 1983 (NAD83) |
| Central Meridian |
0° |
| Latitude of Origin |
0° |
| Units |
Decimal Degrees |
Other projections commonly used for
Texas data include Shackelford, TCMS/LC and TCMS/AEA. The
following parameters define these projections:
| Shackelford |
| Use |
Seamless, statewide
data |
| Projection |
Lambert Conformal
Conic |
| Spheroid |
Clarke 1866 |
| Datum |
North American Datum
of 1927 (NAD27) |
| Longitude of
Origin |
100° West (-100) |
| Latitude of Origin |
31° 10’
North (31.16) |
| 1st Std Parallel |
27° 25’
North (27.416) |
| 2nd Std Parallel |
34° 55’
North (34.916) |
| False
Easting |
3,000,000
feet |
| False Northing |
3,000,000 feet |
| Units |
Feet (international) |
| Texas Centric
Mapping System/Lambert Conformal (TCMS/LC) |
| Use |
Seamless, statewide
data |
| Projection |
Lambert Conformal
Conic |
| Spheroid |
GRS 80 |
| Datum |
North American Datum
of 1983 (NAD83) |
| Longitude of
Origin |
100° West (-100) |
| Latitude of Origin |
18°
North (18) |
| 1st Std Parallel |
27° 30’
North (27.5) |
| 2nd Std Parallel |
35° North (35) |
| False Easting |
1,500,000 meters |
| False Northing |
5,000,000 meters |
| Units |
Meters |
| Texas Centric
Mapping System/Albers Equal Area (TCMS/AEA) |
| Use |
Optimized
for mapping the entire state within a single dataset.
|
| Projection |
Albers Equal Area
Conic |
| Spheroid |
GRS 80 |
| Datum |
North American Datum
of 1983 (NAD83) |
| Longitude of
Origin |
100° West (-100) |
| Latitude of Origin |
18°
North (18) |
| 1st Std Parallel |
27° 30’
North (27.5) |
| 2nd Std Parallel |
35°North (35) |
| False Easting |
1,500,000 meters |
| False Northing |
6,000,000 meters |
| Units |
Meters |
Source: Texas
Natural Resource Information System (TNRIS)
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