Yes this changes the values.
Your values between 0 and 1 are scaled to the new min (0)and max (511) values.
That’s why you get those high values.
Just skip the data type conversion and your values should be fine.
I have a few interferograms created. The last step I applied to each image is the Goldstein Phase Filtering. Exporting these images to Geotiff works, but they don’t open in ArcMap. ArcMap says “Invalid raster dataset. Failed to create raster layer.”
How do I get these interferograms to open and show up in the correct spot with the correct orientation in ArcMap? I understand that due to the aquisition orientation, images can be flipped and/or mirrored. In other interferometry software I have used, I have to take extra steps to get these images to show up correctly in ArcMap. I think there are more steps in SNAP that need to be applied, but I haven’t done this before, so I am not sure what needs to be done.
if you want to display SAR data in ArcMap your last step should always be Range Doppler Terrain Correction. This adds a projection to your data.
You can also directly open the img files from the data folder in ArcMap instead of conversion to GeoTiff. This avoids possible conversion errors.
Yes, that worked perfectly. Thanks. I did see an example of this in a tutorial yesterday too that said the same thing, but had another step. Raster > Geometric Operations > Reprojection. I don’t see why this part has to be done unless you want to export to kmz for a quick view in Google Earth. Do you guys agree?
I have also unwrapped my images, but having an issue viewing the result also. I understand that to unwrap, you have to use snaphu export, then import the result back in. Here is a picture of my exported files using snaphu:
Snaphu Import asks for certain files in each tab, which files do I choose for each tab? What I am doing isn’t working:
1-Read-Phase - Source Product Name: ?
2-Read-Unwrapped-Phase: ?
3-SnaphuImport: Do I check that box? (Do NOT save Wrapped interferogram in the target product)
4-Write: Target Product Name: Target? (I can call it whatever I want right?)
Thanks so much for your help! I know this is pretty easy in concept, but for some reason this step is not working right for me.
reprojecting makes no sense to me as well.
Exporting and importing is not enough, you have to create the unwrapped phase before importing. Please have a look at my tutorial:
Thank you very much, I will have a look and circle back if I have any specific questions.
Do you offer classes online somewhere? I have been doing interferometry for years, but this is the first time using the SNAP software. I would love to learn more advanced skills, tips, tricks with this software. Let me know if you offer anything else you think would be helpful through my journey.
I really appreciate you!
I’m glad I could help.
I’m not offering any courses at the moment, I am just a SNAP user who learnt it by myself.
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Gotcha. Well this forum has been great so far. I’ll just keep using this and a few friends around the world who use it too.
Hi ABraun,
I want to open the img files in the data folder directly into ArcMAP, but it seems strange (the right one).
I have applied “Range Doppler Terrain Correction” after DInSAR and filtering step, projected to WGS84 with lat. and lon…
And I also tried to export the KMZ file for google earth, but it only appeared a part of my result.
Please help me to deal with these problems. Thank you very much!
as indicated in the legend, ArcMap didn’t read the minimum and maximum values of your raster correctly. Therefore it is displayed grey. Change the style accordingly so the data is scaled between -3.14 and +3.14.
Thank you! I got it!
And is it possible to set the zero value as null in SNAP? or I need to process it in ArcGIS? Thank you.
you can define a NoData value in ArcMap directly.
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Hi ABruan, if I import my Beam-Dimap DEM into arcmap, the DEM value changes. How to get rid of it?
how does it change?
The Max - Min values change from 1400mm-450m to 990m - 550m (in arc map).
Both programs have different strategies of stretching the colours over the value ranges. Go sure in the band statistics to see if the absolute min/max values really changed. Many programs cut off the outer 2% of all values in order to exclude outliers from the color scale.
Wont Histogram on arc map represent the real pixel values and distribution?
these values can be trusted I would say.