INP is the dataset of tiepoints, in the format generated by PICREG. It has 800 pixels per line (record), organized as 200 sets of new line, new sample, old line, old sample. Following the last tiepoint is a set of four zero values.
Output triangles dataset. This dataset contains one line for each triangle,
with 12 real values (samples, or columns) per line. The 12 columns are:
1. New line location of uppermost vertex of triangle
2. New sample location of uppermost vertex of triangle
3. New line location of middle vertex of triangle
4. New sample location of middle vertex of triangle
5. New line location of lowermost vertex of triangle
6. New sample location of lowermost vertex of triangle
7. Coefficient C1
8. Coefficient C2
9. Coefficient C3
10. Coefficient C4
11. Coefficient C5
12. Coefficient C6
where OldLine = C1*NewLine + C2*NewSample + C3
OldSample = C4*NewLine + C5*NewSample + C6
NLIN is the number of lines in the input image to the geometric rectification program. It does NOT refer to the size of either the input or output datasets of TRIGRID.
NSIN is the number of samples in the input image to the geometric rectification program. It does NOT refer to the size of either the input or output datasets of TRIGRID.
TRIGRID encloses the input tiepoints with a border of synthetic tiepoints along the borders of the input image. To do this, it selects TOPPTS points, equally spaced along the top (and bottom) of the input image. The three nearest real tiepoints are used to compute the corresponding new line and new sample for each synthetic tiepoint.
TRIGRID encloses the input tiepoints with a border of synthetic tiepoints along the borders of the input image. To do this, it selects SIDEPTS points, equally spaced along the each side of the input image. The three nearest real tiepoints are then used to compute the corresponding new line and new sample for each synthetic tiepoint.
If the input tiepoints are generated by ENVI, enter the tiepoint dataset name here, rather than for the parameter INP.