ALOS-1 L1.5 Terrain Correction

The ‘SAR Mosaic’ does not perform the Terrain Correction.
It just project the data correctly on the ellipsoid.

It should be great if the next updates of S1TBX include the Terrain Correction for the ALOS L1.5 (GRD) images, since the GRD images of Sentinel1 are already supported.

I am aware of that but as you said - at least it gets geocoded and can be used in a GIS.

But I totally agree, it would be helpful if Level 1.5 data would be supported some day.

@ABraun & @gusortiz i agree with you, i hope this will get into the development list soon, i have seen this topic for a long time.

@ABraun [quote=“ABraun, post:11, topic:2927”]
I am aware of that but as you said - at least it gets geocoded and can be used in a GIS.
[/quote]

when you mean it’s good enough for GIS, what’s the accuracy have you ver check it maybe with a base map? i mean a far it is by distance for its real location?

Thanks

I’d say that depends on your application. If there is much foreshortening due to mountainous topography I coudn’t use it for geological mapping. But maybe for water body detection in the valleys it would be sufficient. A comparison with other spatial data (S2, basemap, OSM vectors…) should give a hint about the quality.

@lveci is it planned to have geometric coreection for ALOS-2 level 1.5 CEOS? although it is “geo refrenced” it is nor orthorectified.

this is partly answered here:

not really it’s about ALOS product and not ALOS-2

Hi Gustavo,

I did the trick SAR Mosaic on ALOS 2 L 1.5 and it worked well for the georeference. But I need to do the terrain correction since my study area is in Tapajos and we have some topography in the south and close to the river. How you managed to do the terrain correction? Did you do this is another software?

Many thanks for your suggestions

you can do this in ASF MapReady
This open source software correctly handles Level 1.5 products and performs great with calibrating, terrain correcting (both geometrically and radiometrically) and geocoding your image.

Hi ABraun,
I installed ASF MapReady. I have backscatering images (sigma 0 hh, hv, vh, hh in db) after filter. I am trying to import those images to ASF MapReady, but it is not importing. I also tryed the original images ALOS 2, but the software says that is unable to import it (see the images bellow) . Does it work with ALOS 2? Maybe I did some mistake…
I did the sequence bellow and got the error . Many thanks in advance for your support.


currently, ALOS-2 is not yet supported.

Hi ABraun,

Thanks for your feedback.

It would be nice if this could be fixed in SNAP toolbox or even updated in ASF-MapReady for ALOS 2.
I will try to discover other alternatives.

Cheers

Hi @polybispo did you solve the issue? i’m looking for a similar solution as well.

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using SNAP is it possible to find displacement using this data
Satellite=“ALOS2”
Lbi_Sensor=“SAR”
Lbi_ProcessLevel=“1.5”
Lbi_ProcessFacility=“EICS”

For the map projected L1.5 CEOS format ALOS-2. This tiny software might be helpful.

Hope this would help some people using the map projected L1.5 CEOS ALOS-2.

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Yup this is working

I tried but still shape file is not overlapping

is it shifted or completely outside the image area?

The first option is due to the fact that Mosaic applies geocoding (as a work-around) but not terrain correction, therefore smaller shifts remain.
The second can be a reason of coordinate reference system of the shapefile (e.g UTM instead of WGS84).

No sir, just slightly shifted.

as I said, mosaic applies geocoding to the image but doesn’t replace terrain correction. Unfortunately, the terrain correction of ALOS Level-1.5 products is not supported in SNAP.