Gaps in an image cache for a map service

462
7
12-17-2017 03:41 PM
MarkMindlin
Occasional Contributor III

Hi,

We build and update image cache for a map service.

At some stage, it started to produce gaps (bundles with complete/partially no data) in an updated cache by AOI polygon. Not every time the gap is the same area of AOI.

We compare two counting machine: Local (physical machine) and virtual box.

While we can "fix" the issue on the local machine it is no way to produce good update on the virtual box.

Let’s compare runs on the same AOI.

 

 

Local machine

Virtual box

CPU

16

12/24

RAM

32Gb

96Gb

Parallel processing

95% (means 15)

95% (means 23) /or other run 15

Remote imagery

Y

Y

Remote AOI layer

Y

Y

Local (D:\) cache folder

Y

Y

Local (D:\) input mosaic

Y

Y

Scheme (?)

ArcGIS Online

ArcGIS Online

Arc version

10.5.1

10.5.1

OS

Windows 7

Windows Server 2016

OS bit

64

64

GP 32-bit

Y, Foreground

Y, Foreground

Levels try to build (in one run)

12-20

12-20

Gaps on levels (as a result of run for 12-20 Levels)

12,13

12-17

Repaired by one run per level, 12 Level

Y

No

Repaired by one run per level, 13 Level

Y

N/A

Repaired by one run per level, 17 Level

N/A

No

 

What makes a trouble? 

What else can we compare in order to get closer to a solution?

Desktop 10.5.1. Manage Tile Cache GP. The mosaic had been created in 10.3, then upgraded to 10.5.1

Any help please.

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7 Replies
StephenBarbie
New Contributor

I am having the same issue in 10.5 building imagery cache and was wondering if you were ever able to figure this out. The last time I updated our imagery caches it was done in 10.2.1 and did not have any issues.

It caches fine for the scales 1:4,622,324 down to 1:18,055 but starting with 1:9,027 down to 1:2,256 it starts to leave gaps and does not give an error at all.

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MarkMindlin
Occasional Contributor III

First, we have analysed the overviews, found and removed empty records. It helped for some gaps.

Next, we have removed all overviews. It completely fixed the gaps. When you remove overviews you should change MaxPS values for source raster (category 1)

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PeterBecker
Esri Regular Contributor

Note that a number of improvements and fixes related to caching have gone into 'Manage Tile Cache' in version 10.6 (& Pro 2.1). I would suggest you try using these. They will be out later this week.

Concerning the requirement for overviews. Note that the tool has a "Maximum Source Cell Size" parameter. Lets say you have imagery at 1m resolution you can set the value to 1.5m and for all levels with pixels sizes larger (Ie levels <=16) the levels imagery will be generated by sampling the higher level and so overviews are not required. Use of this parameter depends on the content of the mosaic dataset. If the data is all from one source you may want to not bother creating overviews (to just cache), but use suitably small 'Maximum Source Cell Size'. If you have a mosaic dataset with multiple sources at different resolutions then you might set this value much larger or exclude.

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DanielMcCullock1
New Contributor II

Peter,

When you refer to "Maximum Source Cell Size" and we are using a mosaic dataset, does this refer to the image cell size or the MinPS/LowPS in the footprint table?

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PeterBecker
Esri Regular Contributor

I'm referring here to the "Maximum Source Cell Size" parameter that is part of 'Manage Tile Cache' GPTool. This parameters should be set based on which output levels you want to created by reading the mosaic dataset and which levels you want created by resampling the higher resolution levels in the cache. Has nothing really do to with the Pixelsize values in the mosaic dataset.  Lets say you have imagery in a mosaic dataset that contains NAIP imagery as 1m and Landsat imagery at 15m. If you set "Maximum Source Cell Size" at 2m then you will get a tile cache that at all scales shows NAIP. If you set the value to greater than 15m you will find that the lower levels (resolution) will contain Landsat Imagery.

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MichaelVolz
Esteemed Contributor

Mark:

Did you build a new cache at 10.5.1 or migrate the cache from 10.3?  I would suggest rebuilding the cache from scratch in 10.5.1 so the cache has not been used in any other ArcGIS version than 10.5.1.

I would also suggest building the Raster Mosaic Dataset from scratch as well to see if that addresses your issues.

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MarkMindlin
Occasional Contributor III

Michael,

We have rebuild from scratch. The only 10.3.1 thing is the MosaicDataset. We transform it every time we have an update of the cache.

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