Raster Compression

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12-28-2017 11:27 AM
williamporter
New Contributor II

To fulfill the request of a vendor, I need to squeeze our various years of Digital Ortho Photo Mosaics from 200 - 400 GB each down to 35 GB for each year. They want TIFF format.   It takes many hours - I don't know how many, but more than 6 hours -to copy and compress a raster mosaic from our SQL/SDE data server to my PC. Around midnight I will kicked off the server as other data in the SQL database is updated.  If it takes more than 15 hours it may not be possible.

The vendor specified using 'Create Raster Dataset', but an ESRI tech told me that is designed to combine raster data, not copy.  That doesn't make intuitive sense - I thought raster images had to be sewn together.  I've found little help online for this task.

Is COPY RASTER the best way to do this? 

Is TIFF the best format?  I thought JPEG or PNG were better compression formats. 

Is there a non-iterative way to determine what 50% or 75% compression means in the final product?  I can't believe it's a simple, linear equation; i.e.,  a 100 GB file compressed by 75% becomes a 25 GB file.  But I could be wrong.

I expect a 400 GB DOP mosaic compressed to a 35 MB Tiff to be unreadable, but I was asked to do it, not question it. 

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2 Replies
DanPatterson_Retired
MVP Esteemed Contributor

You can begin by comparing raster compression options on the web... not necessarily those that are directly supported by esri, as these are.

https://blogs.esri.com/esri/arcgis/2010/10/12/a-look-at-raster-compression-pyramids-time-and-space/

do it... versus, can do it, may be two completely different things.  So you might want to do the math for your study area given these examples

XanderBakker
Esri Esteemed Contributor

There are a number of compression types supported in ArcGIS:  Raster compression—Help | ArcGIS Desktop and this page explains how to set those: Setting the raster compression in the environment settings—Help | ArcGIS Desktop 

I really wonder on the "why" of this compression. Did they explain the requirements and is TIFF (not the smallest format available) really necessary? Is changing the resolution an option (Resample—Help | ArcGIS Desktop  or Aggregate—Help | ArcGIS Desktop ). Does is have to be around 35GB or is that the maximum size?

When somebody would tell me to just do it and not question it, that would really make me question it... It would make me wonder if they have any valid arguments to defend these requirements...