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New Contributor
Posts: 2
Registered: ‎03-19-2019
Accepted Solution

PYRX format

I have a problem with new pyramid format .pyrx.

PYRX format is great when it comes on saving memory space.

 

But after pyramid generation on a 16-bit image through Edit Image Metadata function, I get black pixels around my image (Image1.png).

When I set nodata value for the image, I get black pixels across whole footprint of the image (Image2.png).

 

Then I deleted pyramid layers and computed them again several times, choosing every time different downsampling method.

I got black pixels everytime except for SIPS resampling method and ErdasBino3.

 

Do anyone know is this a bug with .pyrx format or I have to choose one of these methods everytime when I compute pyramids?

Also, is there an explanation of downsampling methods?

 

This doesn't happen when pyramids are computed through some other function (like LUT stretch).

 

 

Highlighted
Technical Evangelist
Posts: 816
Registered: ‎10-01-2015

Re: PYRX format

[ Edited ]

Hi Goran,

 

The downsampling methods are explained in the Help for the Create Image Pyramids operator (which should also be linked to from  ImageInfo and Image Command Tool Help pages):

 

https://hexagongeospatial.fluidtopics.net/reader/fH0o7KrMKUViXGUeoilQuA/rEQMQQ4m76v_t_3p7fd3gA

 

Make sure you define the correct NoData for your imagery prior to generating PYRX format pyramids. PYRX uses ECW compression and so is lossy and so you run the risk of turning 0s into non-0s if you haven't defined a NoData mask to be used during the compression process. Your data may not use a value of 0 of course, so pick the correct NoData approach for your data. 

 

By the way - if you decide PYRX isn't the correct pyramid format to use for your purposes then you can set the Preference editor > File Formats > Image Files (General) > Pyramid Layer Generator option to produce RRDs instead (the old format of pyramids). Or you can always pick the Generator method when running ImageInfo, Image Command Tool, or Raster Output in Spatial Model Editor.

 

Hope this helps.

 

Cheers

 

Ian Anderson
Chief Product Owner, Desktop Remote Sensing
Hexagon Geospatial