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What FITS keywords must be present for WWT to load a FITS file properly? RRS feed

  • Question

  • I have radio wavelength images which I would like to add to a tour I'm creating in WWT.  They are created by a software package called MIRIAD.  Unfortunately WWT can't find the coordinates in the image; it displays an error about AVM Metadata being absent.

    I am able to import images from the Spitzer archive so clearly there are some FITS images which are okay.  If anyone knows what the requirements are for WWT to read a FITS file, I would appreciate a rapid response.

    Thanks, Tony

    Thursday, July 14, 2011 9:16 PM

Answers

  •  This is my second attempt at a response. The first one from last Sunday went missing somehow. Maybe I just don't know how to use the new forums.

     

    First you don't want to use *Real* FITS images in tours, you want the processed images. Use Fits Liberator to process them into PNG images with AVM meta data in Photoshop then put them online, preferably tiled using the WWT SDK.

     

    Are the image from the Spitzer really FITS extension images (in black and white) or the Press release images? The press release images are processed into color PNG or JPEG already and have AVM for placement.

     

    Currently FITS and AVM images that can be loaded locally for research use are not usable in tours. The reason is you have a large image file that is stored on your machine, and not public to users. Tours also don't do well with huge images that are not in a tiled-multi-resolution format. Our target for tours is less than 5MZB in size and only a audio track and incidental annotation images really work well. Putting the imaging in a tour will make the user download and playback experience very poor, so images of the sky should be hosted publicly in a tiled format. You then load the images WTML file, select it and add it to your tour.

     

    When tours are created this way they are smaller, and the instant a user zooms in on an image they can see the whole image coming right at them, and as they zoom more, it resolves more detail.

     

    A FITS image by comparison would have been a huge download, and the user would see a monochrome image (with no brightness scaling) and it would take a long time to download. The slide you wanted that image on might be over by the time the image had the change to download.

     

    Now back to the original question. My first try at this was much more long winded and required a lot of cut & paste from code. FITS is a very complicated format, its not really a Standard, but a hodge-podge of common and less common ways of stuffing data into a file package. There are lots of FITS variant that even if we could read, there would be no useful way to see it in WWT. Since we talked on the phone already and I asked you to send me an image and I would figure out what FITS extensions it is using, I will just offer the same to anyone else just e-mail us at (wwtpage at Microsoft dot com) and give us a link to a sample FITS you are having and issue with and we can tell you how to either get it into WWT, or look into what it would take to add support to our FITS reader for the extensions to the FITS format the file is using.

     

    Thanks

     

    Jonathan

    Thursday, July 21, 2011 3:06 PM
    Moderator