20001207: IMGREMAP: MAG= vs RES= (cont.)

>From: Jason Allard <address@hidden>
>Organization: PSU
>Keywords: 200010240345.e9O3jC425238 McIDAS-X IMGREMAP MAG RES

Jason,

>While I thought I had a handle on the IMGREMAP and the IMGCOPY commands
>before, I'm having a little difficulty.
>
>As discussed before, I wanted to change the SIZ, RES, and PLA of the
>image (originally I was going to also change the projection).  Since I
>decided not to change the projection, I was going to go with the
>IMGCOPY command.  It works fine to change the size of the image the the
>place that I put the center lat and long... but it didn't appear to
>change the resolution.  I looked at the IMGCOPY command, and I didn't
>see a RES keyword.  So you can see what I did, here's the command I
>used:
>
>IMGCOPY BWF/071197VIS.9 TEST/71197VIS.2 LAT=54 108 PLA=ULEFT SIZ=360 370 MAG=1
>  RES=8

Right, there is no RES= keyword, so the RES=8 keyword sequence on your
command line is ignored.

>Everything worked fine, except the resolution (I think it didn't
>work)... the new image 'looked' like it had the same resolution of the
>original.  To test this, I changed the RES=8 in the command to 16, 32,
>128, and even 512... and the copied image looks exactly like the
>original.

Right.

>This isn't quite making sense to me, unless you can't change
>the resolution with the IMGCOPY command.

Right again.

>I then tried using the IMGREMAP command, but since I'm not changing the
>projection, it would't let me use the RES or SIZ keywords.  I got the
>message:
>
>IMGREMAP:  Invalid keyword combination...
>IMGREMAP:     The keywords RES and SIZE are not valid for DEST projection

Right.  If you are not changing the projection, you have to be remapping into
an existing image.

>The DEST projection is the default if you don't want to change the
>image... since changing the projection might change the values (as
>discussed before), I want to use the original projection.

OK.

>I guess I didn't pick up on this before because I was working with 8 km
>resolution GOES 7 imagery... but now that I'm working with the 4km GOES
>8 imagery, I want to change it's resolution to 8.

Basically, you want to change the magnification.  For this, you can use
the IMGCOPY command specifying MAG= keyword values.

>Short or remapping the GOES 8 into a GOES 7 image, how do I change the
>resolution...  or is it changed and I'm not realizing it?

Use IMGCOPY.  To see the resolution of the resultant image, specify
the FORM=EXP keyword sequence on the IMGLIST command.

>Thanks for the help,
>Jason

Tom