= distortion =

||Category DART||Version 1.0||

== Description ==
'''distortion''' 


== Input Files ==
 * ./[[DISTORTION.TXT]]
 * ./REGFILES/PICNAME.REG
 * ./make_sumfiles.in


== Output Files ==
 * None


== Important parameters == 
The first line of DISTORTION.TXT determines which parameters the program will solve for. The original Owen model had 6 parameters, E1, E2, E3, E4, E5, and E6. Ordinarily, you only solve for E2, E5, and E6. However, an E4 term also exists, and DISTORTION can solve for it. Here is a list of the options for that first line and what they mean:
 * 6 excludes E4, E5, and E6
 * 8 excludes only E4 (which is a chordic radial distortion)
For a NAC, like DRACO, we don't want an E4 term. We only want E2, E5, and E6. So, we set the first line of DISTORTION.TXT to 8.

The fourth line is an initial guess at the distortion parameters. At the outset, you assume no distortion, so all of these values are set to 0.



== Using distortion ==


distortion
      1089     37547     0.410
     0.021     0.033    -0.068
     0.033     0.040     0.174
  ITERATE? (y/n)


== Using distortion ==

'''Warning!''' A single bad REG file can cause major issues. Before running distortion, ensure that the .REG files have at least 7 stars (file size >1 KB) and that each stars is centered in its red cross hairs in TEMPFILE.ppm. You must be confident in every REG file to ensure that you don't shoot yourself in the foot.

1. Set up [[DISTORTION.TXT]]. The first five lines contain information that control the parameters that DISTORTION solves for.
 * First line: 

8                                   (6 Excludes e4, e5, e6) (8 excludes e4)



2. Run distortion

{{{
shape2mapsA
SHAPEFILES/COVERAGE.TXT
}}}

3. Use [[view_shapeA]] to visualize the coverage on the shape. Note that if you only run [[view_shape]], you will not see the coverage.