nicholas-fong
commented
3 years ago https://dds.cr.usgs.gov/srtm/version2_1/SRTM3 is permanently shut down. I email USGS yesterday and they confirmed that link is no longer supported.
GeoTIFF is fully supported by USGS delivery site. The user interface at the new delivery site takes a LOT of learning but it works. I posted a small Python code to read elevation from USGS SRTM GeoTIFF https://github.com/nicholas-fong/SRTM-GeoTIFF
gdallocationinfo n27_e086_3arc_v2.tif -wgs84 86.925278 27.988056 (Everest 珠穆朗玛峰, 8765 m peak OpenStreetMap) Report: Location: (1110P,14L) Band 1: Value: -32767 (v2 of the USGS GeoTIFF still has voids)
gdallocationinfo n27_e088_3arc_v2.tif -wgs84 88.146667 27.7025 (Nepal Kangchenjunga 8586 m peak OpenStreetMap) Report: Location: (176P,357L) Band 1: Value: -32767 (v2 of the USGS GeoTIFF still as voids)
Download from USGS EarthExplorer (1 Arc-Second) of the GeoTIFF, things look a little bit better:
gdallocationinfo n27_e086_1arc_v3.tif -wgs84 86.925278 27.988056 (Everest 珠穆朗玛峰, 8765 m peak OpenStreetMap) Report: Location: (3331P,43L) Band 1: Value: 8803
Not a bad result: https://oceanservice.noaa.gov/facts/highestpoint.html#:~:text=Mount%20Everest%2C%20located%20in%20Nepal,from%20which%20elevations%20are%20measured. says summit of Everest is 8848 meters
gdallocationinfo n27_e088_1arc_v3.tif -wgs84 88.146667 27.7025 Report: Location: (528P,1071L) Band 1: Value: -32767 <---- still has void
Last attempt: OpenTopography.org, download a GeoTIFF: (presumably this has more processing to reduce voids) https://portal.opentopography.org/raster?opentopoID=OTSRTM.042013.4326.1 Data Selection Coordinates: Xmin: 87.9995833 Xmax: 89.0004167 Ymin: 26.9995833 Ymax: 28.0004167
gdallocationinfo n27_e088.tif -wgs84 88.146667 27.7025 (Nepal Kangchenjunga 8586 m peak OpenStreetMap) Report: Location: (176P,357L) Band 1: Value: 8291
[n27_e088.zip] (https://github.com/aatishnn/srtm-python/files/5973394/n27_e088.zip)
Is anyone able to get the published results for the sample test point: Kanchanjunga, lat: 27.7025, lon: 88.146667?
I've run the author's code, nicholas-fong's code, my code, and the gdallocationifo. None of them come up with the 'correct' elevation.
I think it's a problem with the hgt file I'm using, but can someone else confirm? What are YOU getting?
I downloaded the hgt file from https://dds.cr.usgs.gov/srtm/version2_1/SRTM3. Is there another source? I tried the version1 data with the same result.
Here's the gdallocationinfo that shows the same answer that I am getting.
gdallocationinfo N27E086.hgt -wgs84 86.925278 27.988056 Report: Location: (1110P,14L) Band 1: Value: -32768