Gcp_list.txt and State Plane

#1

I’m trying to build a gcp_list.txt file with coordinates in State Plane, Massachusetts Mainland, NAD83. What should the first line of the gcp_list.txt file look like for State Plane? All I can find online is examples with NAD83 UTM. Thanks!

#2

http://opensfm.readthedocs.io/en/latest/using.html

The first line should contain the name of the projection used for the geo coordinates.

Supported projections
The geospatial coordinates can be specified in one the following formats.

WGS84: This is the standard latitude, longitude coordinates used by most GPS devices. In this case, <geo_x> = longitude, <geo_y> = latitude and <geo_z> = altitude
UTM: UTM projections can be specified using a string projection string such as WGS84 UTM 32N, where 32 is the region and N is . In this case, <geo_x> = E, <geo_y> = N and <geo_z> = altitude
proj4: Any valid proj4 format string can be used. For example, for UTM 32N we can use +proj=utm +zone=32 +north +ellps=WGS84 +datum=WGS84 +units=m +no_defs
#3

@Charlie_Schweik – I usually use https://spatialreference.org for any proj4 strings I need, e.g. searching for http://spatialreference.org/ref/?search=Massachusetts&srtext=Search should give you the state plane coordinate systems you need for Massachusetts.

#4

Charlie_Schweik,

Were you ever able to find a solution for your question? I am trying something similar but using Texas State Plane Central Zone coordinates.

#5

Use the link that was provided in the previous post, search for your projection’s name, and then go to the proj4 parameters string link. Copying the displayed text and pasting it in the GCP list on the first line should do the trick.

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#6

Thanks! I did as you suggested and it worked.

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