GCPFOOT

Description

Converts between feet and meters in existing PCIDSK ground control point segments.

Parameters

Name	Type	Length	Value range
InputGCP: Input GCP segment(s)	GCP port	0 - 1024
OutputGCP: Output GCP segment(s)	GCP port	0 - 1024
Input Units	String	0 - 1
Output Units *	String	1 - 1

* Required parameter

Parameter descriptions

InputGCP: Input GCP segment(s)

Specifies the ground control point (type 213 or 214) segment(s) to convert.

The output segment name and description are retained from the input segment being processed. The input segment and the transformation performed are recorded in the output segment history.

Segments flagged as deleted will not be processed; the warning E023 ("Segment does not exist.") appears, and GCPFOOT goes on to process the next segment.

OutputGCP: Output GCP segment(s)

Specifies the output segment to receive the converted GCPs.

The output segment name and description are retained from the input segment being processed. The input segment and the transformation performed are recorded in the output segment history.

Input Units

Specifies the units of the input segments. If specified, this overrides the units stored in each segment.

Output Units

Specifies the units of the output segments.

Details

Most functions in CATALYST Professional assume sizes and distances are measured in meters. (For "LONG/LAT", it is assumed that the units are in decimal degrees of Longitude and Latitude.) FOOT is a utility program that would normally be run on segment data imported to CATALYST Professional to convert "FOOT" values to equivalent "METRE" values for processing. It can also be used to convert "METRE" values to equivalent 'FOOT' values for processing outside CATALYST Professional.

GCPFOOT transforms coordinates in the input GCP segments (DBSL) in a PCIDSK file.

If the input units (IFUNITS) are specified, the specified units override the units stored in the segment; otherwise, the units from the input segment are used, in which case the segment units must be METRE, FOOT, US FOOT, or INTL FOOT.

The output units (OFUNITS) must be METRE, FOOT, US FOOT, or INTL FOOT.

Conversions

The conversions between the supported units are based on the following conversion factors documented in Appendix A from Robinson [1].

1.0 inch of the "International Foot" equals 25.4 millimetres exactly

1.0 metre equals 39.37 inches for "U.S. Survey Feet" exactly

The following conversion factors were derived from and are compatible with the GCTP software produced by the U.S. Geological Survey [2]:

U.S. survey feet   / metre                  3.2808333333333330
International feet / metre                  3.2808398950131240

metres / U.S. survey foot                   0.3048006096012192
metres / International foot                 0.3048000000000000

U.S. survey feet   / International foot     0.9999980000000000
International feet / U.S. survey foot       1.0000020000040000

References

Robinson, A.H., Sale, R.D., Morrison, J.L., and Muehrcke, P.C. (1984). Elements of Cartography (5th Ed.). New York: John Wiley and Sons

U.S. Geological Survey. National Mapping Division. (1990). Software documentation for GCTP, general cartographic transformation package. Reston, Virginia.