region list: center transformation error for matched image and size conversion accuracy

[kswang1029]

Please refer to the video for the demo. If we create a circle region at (11h, -40deg) and a diameter of 10arcmin, then on a matched image, the center of the transformed circle is shifted (it should be still (11h, -40)).

If we unmatched the image, the copied region has errors in size (should be still 10arcmin) likely due to floating number truncation error.

Jan-12-2021.11-44-36.mp4

@TienHao (or @veggiesaurus) could you have a look?

[kswang1029]

my fault..... this issue exists in v1.4 too......🤢

[kswang1029]

with wide field images, the coordinate transformation may fail thus we see in the region list widget.

Screen.Recording.2021-07-08.at.9.10.30.AM.mov