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New Contributor
Posts: 3
Registered: ‎03-24-2018

How to fix the layer stack composite of an image

I am pulling my hair out trying to understand how to export a TIFF image from ERDAS where the band composition is fixed as RGB and cannot be misinterpreted in another software. I am testing a supervised classification system on Picterra and when I upload a 8bit unsigned 3 layer image it reads it incorrectly and puts the bands in the wrong order. I would like to fix the band composite please tell me how to do this!

 

Thankyou Smiley Happy

Technical Evangelist
Posts: 832
Registered: ‎10-01-2015

Re: How to fix the layer stack composite of an image

Hi Isla,

 

First off - What band order is your data in? RGB or BGR? Or, indeed, does it have more than 3 bands?

 

Knowing that we can narrow things down. Oh, and what version of ERDAS IMAGINE?

 

I'm not familiar with Picterra - what band order does it expect a 3band image to be in? Band 1 = Red, Band 2 = Green, Band 3 = Blue I assume, but want to confirm.

 

Cheers

 

Ian Anderson
Chief Product Owner, Desktop Remote Sensing
Hexagon Geospatial
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New Contributor
Posts: 3
Registered: ‎03-24-2018

Re: How to fix the layer stack composite of an image

Hi Ian,

 

Thanks for the assistance. The file is in RGB order (just 3 bands) and Picterra should be reading it as RGB but it is failing to do so as it seems to reorder the bands. I am using version 16.5  of ERDAS. I want to export so the bands are stacked together in a fixed format as a single geotiff so Picterra reads it in a correct order. 

 

Your help is much appreciated.

 

Thanks

 

Technical Evangelist
Posts: 832
Registered: ‎10-01-2015

Re: How to fix the layer stack composite of an image

What does it look like in Picterra? Greyscale or reversed color order?

 

Ian Anderson
Chief Product Owner, Desktop Remote Sensing
Hexagon Geospatial
New Contributor
Posts: 3
Registered: ‎03-24-2018

Re: How to fix the layer stack composite of an image

Technical Evangelist
Posts: 832
Registered: ‎10-01-2015

Re: How to fix the layer stack composite of an image

Hi Isla,

 

When you run the Exporter you use options like this?:

 

export_Tiff.png

 

If so then I'm not sure why Picterra wouldn't interpret the data as RGB being bands 1,2,3. The Photommetric Interpretation tag should be set to RGB (you can check using ImageInfo) and other software should be capable of using that to set the default display parameters.

 

Do you know what default LUT stretch Picterra applies when displaying data and is it the same as the stretch you're using in ERDAS IMAGINE (which by default should be a 2.5% / 1% percentage linear)?

 

You may want to contact your local support (Geospatial Insight), or even contact Picterra's support, to try to pin down what the issue is.

 

Cheers

 

Ian Anderson
Chief Product Owner, Desktop Remote Sensing
Hexagon Geospatial
New Member
Posts: 1
Registered: ‎04-23-2019

Re: How to fix the layer stack composite of an image

Hello,

This is Julien from Picterra. I just found out about this discussion.

 

As Ian pointed out, we should interpret RGB geotiff currently: we use gdal to extract the photommetric interpretation tag and figure out which band is what.

 

If the data is RGB uint8, we display the image as-is. Otherwise, it undergoes what we call 'normalization' (including LUT stretch as Ian mentioned), which is explained in more details here :

https://picterra.ch/knowledge-base/normalization-process-for-the-uploaded-images/

 

So if this is not working, it is possible we have a bug in the way we handle geotiffs coming out of erdas. If that is the case, please reach out at support@picterra.ch and we'll have a look at the particular file.

 

Best regards,

 

Julien Rebetez

Lead Software & Machine Learning Engineer

Picterra SA