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07/20/2005

Warp

The Data Cube Tool has a warp button, new with version Lx43.

Notes (as of version Lx43):

The Outliers button has been removed.  Functions to clip outliers (pixels out of range) are in the cube button.

The warp button allows one image to be warped into another by using tie points.  As of Lx43, the warp functions are bi-linear, quadratic, cubic, etc.  Once the tie points are recoreded, a folder of images can be warped using them, via either the warp button or the Process Folder Tool.

Warp Menu

 Please use the control key to get documentation on these functions.

 Collect tie points - ON, starts a loop during which you can view one image or the other using the shift key, and click on tie points that connect matching features in both.  The control key stops this loop.  The warp button turns PINK when the loop is running.  The tie points are collected in a list in memory

Upon stopping the collection loop, the tie points are listed in a text window.  To save this as a tie point file, use File / save TEXT.

The shorthand notation using slashes (as above) is explained here, as well as here.


How to 'unwarp' a series of images.

Collecting Tie Points

  1. Load a series of images into the Data Cube Tool, using Read / as image files.  The cube must contain at least two images, which are the 'clean' (not warped) image and the warped image.
  2. Select the cube with the cube! button.
  3. Select the clean image with the ref slc! button, and the warped image with the flick slc! button.
  4. Turn on the tie point collection loop with  Warp / collect tie points - ON.  Collect as many tie points as you need.
    1. Use the shift key to shift from the clean image to the warped one.
    2. Select a feature that appears in both images.  Click on it in the clean image, then, shift-click on it in the warped image.
      1. When you click on the clean image, a small circle appears over the feature.
      2. Then, on shift clicking on the same feature in the warped image, a number will replace the small circle, and a line will run from the number to the clicked position in the warped image.
      3. The number is the index when the tie points are listed.
    3. This process may be halted (with the control key) and restarted later.  Only immediately after restarting, you may have to hit the shift key to get the image to display properly.
    4. Tie points may be deleted using warp / delet tie points, while the loop is running.  The remaining tie points will be renumbered.
  5. When the loop is halted with the control key, the tie points are listed in a text file.  This file is not saved automatically.  When the list is finished, save this text window to a file using File / save TEXT (in the Lispix menu bar.)
  6. This tie point file is loaded at a later time using warp / load tie points.

 

Unwarping Images

  1. Open a data cube with at least one image which you want to unwarp.  This image must be the same size as the images from which the tie points were collected.
  2. Select the cube in the Data Cube Tool with the Cube! button.
  3. Load the tie points:  warp / Load tie points.
  4. Make the x and y warp maps:  warp / Make warp shift maps.  These images must be there when any images are unwarped.  They can be saved as files and loaded later, but it is just as fast to make them directly from the tie point file.
  5. Unwarp an image using warp / unwarp image, or a folder of images using warp / unwarp folder.
  6. A folder of images can also be unwarped using the Process Folder Tool, and its warp command.  The warp maps need to be open when this is done, but no data cube need be open.