Framing & Mosaic Wizard for large mosaics


#1

Hi,

I am trying to use the SGPro to create a large wide-angle mosaic (160x90 deg) but the framing wizard cannot download images larger than 16x16 degreees. Would it be possible to add manual mosaic configuration, where a user specifies the RA&DEC coordinates for two corners and the wizard would generate the exposure sequence?

Thanks,
Alex


Here's how to do a large mosaic
#2

This seems really large for a mosaic. Have mosaics this size worked from smaller tiles to complete such a large scale image?


#3

There is no published limit for the MFW, but practical limits seem to be around 20 degrees. It is on our list of things to do to gather data and provide empirical constraints to the help manual.


#4

Hi Christo, yes and quite successfully. Please have a look at Axel Mellinger’s work:
http://www.milkywaysky.com/


#5

Hi Ken,

Indeed the image download never completes for mosaics larger than 20 degrees. It would be great to have the ability to bypass the image download and specify two corner coordinates manually. Then the Wizard would figure out the panels according to overlap.

Is that something that can be done?

Cheers,
Alex


#6

Hi to all,

by using the query form on the skyview server I get the wanted image (M8, 3000x3000 pixel, FOV 30°, survey=DSS) within 5-6 min.
Only changing the survey to DSS2 red results reproduceably in a connection interruption after 10-12 min.
I guess the survey used by SGPro (dss2r) is the same as DSS2 red in the query form on the server.
Maybe this is the reason of the large mosaics issue of FMW. I think the issue is on the skyview server. Give another survey a trial!

Could You implement to FMW the possibility to choose the amount of pixels of the queried image? Especially for greater FOV’s the default value (1500) is rather small.

Cheers,
Helmar


#7

We’d prefer not to expose every detail of the MFW through settings, but maybe we can consider adjusting based on FoV (or just make all of them larger). 1500x1500 was a result of much fetch testing (seemed like the best compromise between download size, consideration for the creating servers and useful resolution to the users.

That said, I am not sure I understand what you are after here. Are you saying that the image size param is somehow affecting your ability to get a canvas back or that the canvas comes back, but is not usable (or maybe something else entirely)? SGPro uses some small amount of logic to try and find the best survey (especially since DSS2 is not complete).


#8

Hi Ken,

no, image size param is just a feature request and independent of the large mosaics issue of FMW.

I didn’t realise this as in my fetch testing MFW only used dss2r as survey.
As said above fetch testing by using the query form on the skyview server was successful (FOV 30°, survey=DSS) and failed when using DSS2 red. So I came to the conclusion that switching the survey to DSS could solve the problems in getting great canvas. Maybe I’m wrong.

Helmar


#9

Do you mean SGPro switching? At one point SGPro used DSS exclusively until we came to the realization that if DSS2 can provide the canvas it will almost certainly be of higher quality with better contrast (important for selecting nebulous areas). Because of this DSS2 is the first choice, but not the last (upon failure).


#10

Hi Ken,[quote=“Ken, post:9, topic:4927”]
Do you mean SGPro switching?
[/quote]

exactly.

In the meantime I made some more testing on the skyview server’s query form.
Using Firefox I get an errormessage ‘connection resetted/brocken’ if there is no server response after 11 minutes, no matter whether I use DSS or DSS2. For the DSS survey test I requested a canvas with 60° FoV which could obviously not be finished within the 11 minutes.
The same test with the Internet Explorer (DSS, 60° FoV) failed after 1 hour with the errormessage ‘no response’.
I believe the problems with getting great canvas are caused by overload of the skyview servers and that the DSS survey works better than the DSS2 survey in this case.
Is it possible to implement another solution for great canvas, i.e. images of your own which are already solved?

Cheers
Helmar


#11

Right. So just to be clear. I explained the thought process above so, as of now, there is no “in the meantime”. We are partial to the way survey selection operates now, but may consider possibly increasing resolution… We don’t claim it’s perfect, but we feel, in most cases it provides the best results.


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