APOLLO & ECW/JP2 Discussions

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Occasional Contributor
Posts: 11
Registered: ‎01-03-2018

White Holes appears on Elevation Data Stored in ECW Format

Hi team,

 

For display purpose in ERDAS Apollo, we've converted the elevation data in GeoTIFF floating points format to ECW raster image (8bits format).  After creating WMS, we found out a lot of white holes when zooming in the datasets.

 

We've checked this dataset using the desktop software, ERDAS Imagine and there are no white holes inside the data.

 

I've attached the sample of white holes appears on elevation data.

 

Please advice.

 

Thanks.

 

Regards,

Munirah Shaffie

 

 

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Moderator
Moderator
Posts: 382
Registered: ‎11-16-2015

Re: White Holes appears on Elevation Data Stored in ECW Format

Hi Munirah,

 

It looks like the "0" values are treated as null data during the compression process and/or by the APOLLO service.

Which APOLLO service are you using? How have you converted your GeoTiff into ECW?

 

Florent

Highlighted
Occasional Contributor
Posts: 11
Registered: ‎01-03-2018

Re: White Holes appears on Elevation Data Stored in ECW Format

Hi Florent,

 

We're consuming WMS to display the dataset using Geomedia Desktop and we use Global Mapper to convert GeoTiff into ECW.  The setting that we used as attached file.

 

 

 

 

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Moderator
Moderator
Posts: 382
Registered: ‎11-16-2015

Re: White Holes appears on Elevation Data Stored in ECW Format

[ Edited ]
  • If you use an APOLLO Core service or the catalogWMS with the Core chosen as raster provider (see configuration wizard), you can try to uncheck "Make Background (Void) Pixels Transparent" in the Global Mapper export:
    Setting.JPG

  • If you have chosen the legacy WMS for the catalog (during the configuration), it means that APOLLO is automatically masking the "0" values and not sure there is a solution (maybe trying to change the null value in the dataset catalog properties). Or you need to better prepare your data: add a transparency layer and avoid "0" values). The workaround would be to reconfigure APOLLO and switch to the Core for the catalog WMS (beeing aware of some limitations).
  • If you have created a legacy service ("Services" in Data Manager), you need also to change the background value, see "BACKGROUNDVALUE": https://hexagongeospatial.fluidtopics.net/reader/3rX2Rf~XpgzYLMH8aG8gEw/x8LHrcm3eGD08VNGDwV4TA (just add the parameter in the provider and choose a number outside your image range)

 

But in general, the advise is to add a transparency layer to the ECW (and avoid "0"values if you use the legacy catalog WMS).

Highlighted
Staff
Posts: 138
Registered: ‎05-31-2016

Re: White Holes appears on Elevation Data Stored in ECW Format

If you are using the Legacy WMS for the provider you can set the "NULL Values" property for the Aggregate to -1 (actually setting it to any value that is out of range will work) to disable null values in ECW files.

When you do this only the regions defined as transparent in the ECW will appear as transparent.