Weblog

A summary of work I've done at the Space Telescope Institute.

Tblot

I modified the code to doblot, similar to the way I modified dobox to fix the off by one problem with the new pixel mapping. I wrote the first unit test, but ran into a puzzle where the calling sequence of the interpolation routine doesn't seem to match how it is being called.

Posted on 15 Sep 2014

Another One Down

I wrote unit tests for dobox and go them to pass. These tests also tested the turbo kernel, which is the next highest priority after the square kernel. Dobox is the top of the hierarchy of code that needs to be tested for errors after rewriting map_value. But I still need to make parallel changes and tests for doblot, which also calls map_value.

Posted on 12 Sep 2014

Solved But Not Satisfied

I've written enough tests to satisfy myself that my change to the indexing in do_kernel_square is correct. But I still have questions about how the flux is summed in the code. This is code I haven't touched and should be unaffected by my changes. I will ask about that tomorrow.

Posted on 11 Sep 2014

More Tests

I got the existing tests to pass the code after the one to zero code transition and wrote some more. There are still a few problems that need clearing up.

Posted on 10 Sep 2014

Back Tracking

I dumped the half pixel grid, as it took too long. I got all the test cases to run and then modified the cdrizzlebox code to be zero based instead of one based. This is necessary because we now have a pixel to pixel mapping instead of a WCS to pixel mapping in the code and pixel coordinates are zero based.

Posted on 09 Sep 2014

Fixing Something

I got all the tests working again and modified the pixmap code to create a float array instead of a double and use a half pixel grid. The latter change is going to slow things down when computing the mapping, so I'm not sure if I'll keep it.

Posted on 08 Sep 2014

Reassessing

I took a step back and studied the code and asked Warren some questions about it. I believe I now have a good handle on how the square kernel works. There's a problem: some of the code assumes one-indexing instead of zero-indexing. I do not believe this is still valid after I changed the cdrizzlemap code. Everything should now be zero-indexed. But tracking down all the locations will be a little tricky.

Posted on 05 Sep 2014

Forward Motion

I got the first test case of do_kernel_square, which does no scaling, to work. Next step is to figure out all the scaling options and coordinate offsets so I can make sense of the code and write more tests.

Posted on 04 Sep 2014

Patience Is a Virtue

I solved the segmentation violations and got do_kernel_quare to run without crashing, but not much more than that. Trying to figure out the code which sums the image contributions and see why it isn't doing what I expect.

Posted on 03 Sep 2014

Next Up

I got all my tests for check_over to pass and moved on to writing the first test for do_kernel_square. Unfortunately, it dumps core. So that is the next problem to solve.

Posted on 02 Sep 2014