Pyramids - are they used by image server?

Question

I'm fairly new to image server (v9.3.1) but I'm wondering if normal pyramids (.rrd files) are used by image services? I gather service overviews, derived tiles and rasters have some sort of pyramiding functionality, so I can't see there is a need to keep the .rrd files if the imagery is only served up by image server.

MelanieHarlow · Answer

If you create internal pyramids on the generated "service overviews" and/or "derived tiles", would image server use these pyramids also?

Please do not build pyramids on your service overviews. This is not recommended. These are generated within specifications that do not require pyramids. (You can think of them as pyramids for your ISDef)

PeterBecker · Answer

Yes the technology uses any existing pyramids. The system does not necessarily use all the levels though. When a rasters is added the system computes the LoPS and HiPS values for the rasters. The LoPS is based on the high res imagery, the HiPS is based on the availability of pyramids and their size. Generally the HiPS is set to the size of pixel in the pyramid where the NCols>1500. What this attempts to do is ensure that the larger pyramids are used by not the very small ones. At the larger scales is it better to create overviews that are a mosaic of multiple images so that the system does not need to open a large number of files at smaller scales. All these value can be manually changed by using the Calculate tools.
V10 is better then V9.3 in that the overviews are automatically used if they exists. In V9.3 when ingesting the imagery the system looked to see if the overviews exist and if they were added later it would not recognize them.

DallasShearer · Answer

If you create internal pyramids on the generated "service overviews" and/or "derived tiles", would image server use these pyramids also? Given they adhere to the "Number of cols" rules stated previously?