WWT & VO (was NG of GS & BO standards for JPEG with WCS)

Alberto Conti aconti at stsci.edu
Fri Jan 18 10:34:11 PST 2008

> One is the OpenGIS Web Map Service (WMS), which is designed for rapid
> remote visualization of graphical data.  With the addition of some
> astronomy oriented projections this could work well for graphical
> data from astronomy.  Unlike SIA, WMS does not require a prior query
> for data access, and instead allows direct access at the pixel level
> to seamless, wide area graphical imagery.
At STScI, Antonio Volpicelli, Brian McLean and I have been  
experimenting on this for some time now.
It turns our that GoogleSky can "hook" directly onto WMS servers. I  
assume WWT can/will be able to do that as well, but I don't know.

We have built a full sky map of GALEX data that drives our in-browser  
map application (http://mastmap.stsci.edu/galex/). The same data is  
fed to GoogleSky. We had a poster at the AAS on this (047.28) Web  
Mapping Services Technology and Astronomical Data (http:// 

WMS seems to be a rather nice framework, lacking only proper  
astronomical projections.


> On Thu, 17 Jan 2008, Jonathan Fay wrote:
>> As far as WWT we are planning to document all our data access  
>> interfaces, and open them up some time after we go live pending  
>> legal review.
>> We have a cutout service, a high-speed tile service, and a  
>> reprojection/compositing service that are currently used internal  
>> to WWT that may be opened up as the interfaces stabilize and we  
>> confirm the legal status on the data to be served.
>> The reason they exist, rather than hit the VO sources directly is  
>> they are highly tuned for large scale visualization across the  
>> sky. No current VO service is designed to service that need, so it  
>> was necessary for us to implement that service, as well as a new  
>> projection to allow full 3d sky access efficiently without  
>> singularities. The full sky tile sets are meant to be reprojected  
>> with 3d hardware, a software reprojection is necessary for  
>> integration of them into 2d imaging applications, thus our cutout  
>> and reprojection service.
>> It may take a while for external access to get rolling on this  
>> given the new projections, but the cutout server one it is  
>> released should be useful for applications fairly quickly as in  
>> gives a TAN projection back as JPEG or PNG image, and won't  
>> require reprojection for display.
>> Most of this data is sourced from VO sites thru the VO interfaces,  
>> but we reproject and tile as necessary to make it scale well. For  
>> instance Hubble publishes press release images thru a SIA query  
>> and VO Table. Some of which are 16k x 16k and over half a  
>> gigabyte. These images are beautiful, but too large for public  
>> download. They must be turned into tiled multi-res pyramids to be  
>> served on mass scale efficiently. Other VO services had full sky  
>> data, but the data must be projected into a tiles multi-res mosaic  
>> for visualization. That operation is not real-time friendly, but  
>> once that work has been done the result is a useful service that  
>> should (and will be) made available to others to use.
>> Related to your other question is that WWT will also natively open  
>> AVM encoded images (currently a IVOA note) and display them  
>> directly in the sky. The last details of V1.1 of the proposed  
>> standard were hashed out at a meeting at AAS last week. Spitzer,  
>> Chandra and Hubble images are all going to be encoded with AVM,  
>> and many already are.
>> WWT Pro, that we are co-developing with Harvard IIC/CFA will be a  
>> very rich VO client for interacting with VO images,  catalogs,  
>> footprints, events, etc. While it is entirely possible to have all  
>> this functionality in the wide release version of WWT, we don't  
>> want to overload the existing VO infrastructure.
>> Jonathan Fay
>> Principal Research Software Design Engineer
>> WorldWide Telescope
>> Microsoft Research
>> -----Original Message-----
>> From: owner-interop at eso.org [mailto:owner-interop at eso.org] On  
>> Behalf Of Pierre Fernique
>> Sent: Thursday, January 17, 2008 12:17 AM
>> To: interop at ivoa.net
>> Subject: Re: next generation of Sky in Google Earth
>> Dear VO members,
>> I would like to bring the discussion to another point related to  
>> the VO
>> and Google Sky/WWT.
>> I would like to ask to Google sky team and Microsoft WWT team if  
>> it is
>> possible to create my own client accessing their image data base. For
>> instance, if I want to add a dedicated Aladin layer displaying the  
>> HTM
>> sky background images from Microsoft data base, or the sector base  
>> sky
>> background images from Google, could I ? 1) Is there open  
>> standards for
>> that and I can develop my own client ? 2) Could I have to plug a  
>> kind of
>> proprietary libraries in Aladin ? 3) Or perhaps it is not possible at
>> all (technically ? strategically ? no documented ?) Obviously, the  
>> first
>> solution will be the best for my VO point of view.
>> I really appreciate to offer to Aladin users these astronomical data.
>> Exactly in a symetric way that WWT and Google Sky use Simbad opened
>> standards (object resolver, ...), or VizieR catalog access, and  
>> other VO
>> access..
>> Pierre Fernique

Dr Alberto Conti
Community Missions Office
Space Telescope Science Institute
contact | tel: 410-338-4534 | aim: wscience

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