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DCL:GRPH1:STPACK: Transformation Function

6.1 Summary

STPACK is a collection of functions that handle transformation between coordinates. The coordinate transformation can be divided into the following three steps:

• Normalization transformation
• Perspective transformation
• Workstation transformation

The normalization transformation can further be divided into the following transformations.

• Transformation of units for angle (radian and degrees)
• Rotation of map coordinates
• Basic transformation

Here, basic transformation refers to the essential part of normalization transformation, and in a rectangular coordinate, is the normalization transformation itself. In a map projection coordinate, the basic transformation is the transformation after the rotation of the coordinates (transformation by MATH1/maplib). In a basic transformation, the angle is always represented in radians.