|
|
| Re: Warping with intensity conservation or drizzle algorithm [message #60919 is a reply to message #60790] |
Sun, 15 June 2008 14:35  |
wlandsman
Messages: 743
Registered: June 2000
|
Senior Member |
|
|
On Jun 13, 9:00 pm, Giorgio <giorgiol...@gmail.com> wrote:
> Hi,
> Does anyone know if there is already a warping with intensity
> conservation implemented in IDL? Or an implementation of the drizzle
> algorithm?
I don't know of anything that would work out of the box. But if you
don't find anything else and want to stick with IDL and are willing to
do some work, here are some ideas:
(1) If you download the IDL pipeline for the SIMPLE (Simple Imaging
and Mosaicking PipeLinE)
http://www.aoc.nrao.edu/~whwang/idl/SIMPLE/index.htm by Wei-Hao Wang,
you'll find a program warp_im.pro that uses first warps using
POLY_2D() but then conserves intensity by multiplying by a map of
pixel area ratios. I haven't tried this to see how well it works.
(2) JD Smith's CUBISM software (http://turtle.as.arizona.edu/jdsmith/
cubism.php ) uses an algorithm similar to drizzling to resample 1-d
spectra. The workhorse procedure for this algorithm is called
polyclip.pro and it performs Sutherland-Hodgman polygon clipping.
He also provide a C version which is 50 (!) times faster. (So
let's encourage ITTVIS to include Sutherland-Hodgman clipping or
something similar as an intrinisc IDL function.)
(3) Tom McGlynn provides a Java class implements a fast flux
conserving resampling based on the Sutherland-Hodgman clipping
algorithm at http://skyview.gsfc.nasa.gov/polysamp/ It looks like
this would be easy to implement with the IDL-Java bridge though I
haven't tried it, and one would still need to implement the
reprojection software.
--Wayne
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
