How to project raster without promoting and avoid to change NoData for 0 values?

2020
8
06-14-2017 08:15 AM
GlibaRoland
New Contributor III

Hello Everyone!

I am trying to solve a follow problem. I got a bunch of tiff and after projection ArcGIS ask me to promote the pixel depth to keep NoData value and without it the result is an ugly black frame as NoData value. I red the NoData enviroments description but I don't understand. Why can't I project it with settings of NoData=None and without promoting to get the raster without black NoData?

NoData (Environment setting)—Help | ArcGIS for Desktop 

"

  • NONE—There will not be any NoData value rules in place. If your input and your output have the same value range, the NoData will be transferred over without any changes. However, if your value range changes, there will be no value for NoData in your output. This is the default method."

So in and output also are tiff. maybe changed the value range? how? or what?

Thank you for any help! very much!

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8 Replies
SimonWoo
Esri Contributor

The value range refers to the bit depth (pixel depth) of the raster file. For instance, an 8bit unisgn raster can only contain pixel values from 0 to 255.  If you want to add a NoData value, you can specify the NoData value to remain within the 0-255 range.  But ArcGIS cannot automatically choose a default value between 0-255 since there may be valid pixel values there.  The only pixel value that the software can insure is not being used is a pixel value that does not already exist in the the data - a value in the next bit depth. 

You can keep the pixel depth the same, as long as you specify how to automatically choose the NoData Value.  So the valid keywords you can use (in the page you already found) are:

  • MAXIMUM—The maximum value in the output data range will be used as your NoData value.
  • MINIMUM—The minimum value in the output data range will be used as your NoData value.
GlibaRoland
New Contributor III

Thank you for the help.

I am trying to use mapup mapdown etc options in the raster storage(enviroments) but as I see neither works. So in all of these cases the result is the same: nothing pixel value change (in mapup, mapdown) it does not promoted (promote option) and in raster properties the nodata value is the same 256 instead of 255. Any idea why is it not working?

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SimonWoo
Esri Contributor

Only MAXIMUM and MINIMUM are valid for not promoting the bit depth.

GlibaRoland
New Contributor III

Neither of the NoDATA options (min-max-map-up-map down, promotions none) does not work  The result is the same, still 256 is the NoDATA value and my "black frame" is still black with 0:0:0. values. I tried to give manually 0 value for NoDATA with raster properties tool) but in this case many of inner cells that contains at least one 0 value is empty cause of being NoData. How should I define exactly 0:0:0 for NoDATA if NoData settings in the enviroments does not work? Thanks for help!

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GünterDörffel
Occasional Contributor III

Are you still working on file-rasters or on a MosaicDataset? In a MosaicDataset there is a Tool (Define MosaicDataset NoData) that is very versatile and will allow you to specify NoData in many inclusive and exclusive ways. The result is a mask process. So again I recommend: Make it a MosaicDataset 🙂

Just to check your data: If you specify 0:0:0 as the background value in the Properties of a layer generated from your data - is it then interpreted correctly?

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GünterDörffel
Occasional Contributor III

An alternative to projecting the rasters at all would make sense if you plan to use them together and in different projections:

Add them to a mosaic dataset defined in the SRS the data is in. The footprints (and boundary) will then be defined excactly the same way as the original tiffs - so no need for NoData values. If you then use the MosaicDataset in the new projection (dont forget to set transformations needed in the MosaicDataset properties), there will be no NoData problem from the on-the-fly projection , thats made sure by the vectors of the footprints and boundary.

On the fly projection is computation, yes. On the other hand there will always be only one single resampling when using a MosaicDataset. Thazs much better than a resampled datatset due to the projection and another one due to the screen-resampling for display. Give it a try. For discrete data it will make a big difference, for orthos it would probably not be that important.

GlibaRoland
New Contributor III

I'll try. Thank you for the idea. But it is an alternative option as a solution. May would it be faster with mosaic than in separated files? These are ortophotos for basemap.

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GünterDörffel
Occasional Contributor III

If you want to create a "basemap" from your Orthos, MosaicDataset is the way to go. Please read Imagery: Data management patterns and recommendations—Help | ArcGIS Desktop  

and even more specific: Image Management in the "old" resource center, and there the "PreProcessed Orthophotos" section

This is an easy workflow. As written above, do not "de-value" your original imagery by projecting files. 

Regards
Guenter

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