User's Guide

PROJWIND

Creates an alias with a window specification from projection coordinates

Function:

Creates a valid image window specification in lines and samples from a window specification containing projection coordinates. The resulting window is placed in an alias.

Parameters:

IN
Input image. The input specification with a window in projection coordinates. The projection coordinates entered must be in the same projection coordinate system as the information in the image DDR. Subbanding is permitted, but only one image specification may be given. Window format is (starting Y coordinate, starting X coordinate, delta Y, delta X).

ALIASNAM
Alias name. The name of the alias to be created--an alphanumeric string up to nine characters long beginning with "$".

Example:

  1. LAS> projwind in="my.image(3932050.0,462925.0,12800.0,12800.0:1)" aliasnam=$image1

    The input image specification is parsed and the window of projection coordinates is extracted. Using the DDR information from MY.IMAGE, the projection coordinates are converted to a line, sample window. The new image specification with image name, window in image coordinates, and band specification is written to the alias $IMAGE1.

Description/Algorithm:

The user enters an input image specification and an alias name. The input image specification is the standard LAS image specification, except that the window is in projection coordinates. Window format is (starting Y coordinate, starting X coordinate, delta Y, delta X). The projection coordinates must be in the same projection system as the information in the input image's DDR. If the projection information in the DDR is not valid, this function will abort with a fatal error.

The input image specification is parsed and the window of projection coordinates is extracted. Using the DDR information, the projection coordinates are converted to a line sample window. The new image specification with image name, window in image coordinates, and band specification is written to the alias name.

Nonfatal Error Messages:

    None.

Fatal Error Messages:

  1. [projwind-fatal] Fatal error encountered

    The error message that is displayed immediately preceding this message is the specific error that was encountered. Processing is terminated.

  2. [projwind-noproj] Projection information no available

    The input image DDR does not contain enough valid projection information to convert projection coordinates to image coordinates. The projection fields in the DDR must contain valid information for PROJWIND to execute.

User Note:

  1. PROJWIND only allows one image as input. Therefore, if one wishes to use IN="IMAGE1 + IMAGE2 + IMAGE3", PROJWIND must be run three times and then IN="$ALIAS1 + $ALIAS2 + $ALIAS3".