Esri Mapping Center - Ask a Cartographer

Interlaced pngs for tile cache?

February 03 2011 | 2 comments
Categories: Web Maps

Hi,

I know that Arc10 will provide mixed caches, with using PNG in the middle and JPEG around the outside of the tiled area (I think), to save storage space. I'm still at 9.3.1, and am wondering:
1) can ArcGIS Server create interlaced PNG files for a tile cache?
2) can AGS consume interlaced PNGs in a tile cache, if they're created another way?

Thanks.

Mapping Center Answer:

1) Can ArcGIS Server create interlaced PNG files for a tile cache? No, both ArcGIS Server 10.0 & 9.3.1 do not support creation of interlaced PNG files. Note: Please correct me if you are referring to "interlaced PNG" files in the same way as I am. 'PNG interlacing (formally known as Adam 7) begins by only reading a small percentage of all the data and filling in the empty spaces with an interpolated color value. For every time step, more information is rendered, replacing the "in-between" interpolated colors with the real colors until finally all the data is loaded and rendered.'

2) Can AGS consume interlaced PNGs in a tile cache, if they're created another way? No, we do not support interlaced PNG in a tile cache. Although theoretically there is no reason why it shouldn't work, but we cannot comment as we haven't tested it.

thank you! posted by john shramek on Feb 10 2011 3:34PM

Yes, I'm referring to interlaced png files in the same way. I heard that they were supported in ImageServer, and thought it would be great if I could generate and/or use them in tiled ArcGIS Server services.

Benifits of using Interlaced Png's posted by Garima Tiwari on Feb 15 2011 4:48PM

ArcGIS 10.0 Image Server does not support the “Interlaced Png” format.

Using “Interlaced Png” as cache image format would slow down the caching time and would increase the size of cache on disk, apart from this it is not clear if it is supported by all the browsers. The real requirement for using interlaced Png’s will be when several users are consuming cache tiles over network with very low bandwidth speeds, in which case the benefits will outweigh the costs discussed above.

However, if you feel that there are other benefits of using "Interlaced Png's" as cache image format or for Image services, please feel free to submit this as a software enhancement request on our ArcGIS Ideas page. The link to that Web page is ideas.arcgis.com. You may find that someone has already submitted the idea, in which case you can vote to support it. If not, then you can submit the idea yourself!

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