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DEM ( Digital Elevation Model ) extraction is one of popular topic in GIS and Remote Sensing. There are so many ways and methods to produce a DEM. You can use survey data in points format then interpolate it to became raster DEM, or using contour lines to generate DEM. Almost every GIS and Remote Sensing can do this kind of analysis. The better approach and yielding a better result is using Photogrammetry techniques. For photogrammetry, you needs satellite imagery or aerial photographs that has image overlap between flight line that later can be opened together in a photogrammetric software, and then from the overlaps, height and elevation information could be reconstructed and sampled together in their respective grids, and finally a DEM has been created.  Recent development of survey technology has introduce us to LIDAR technology that enabling us to get a DEM in superfine resolution and covering large area. UAV technology is also progressed so much even photogrammetry survey can...

Tulisan ini berangkat dari postingan saya dua tahun yang lalu di SINI dan di SINI . Setelah lewat dua tahun, saya semakin memahami konsep, proses dan metode teknis dari INSAR. Kunci pentingnya sudah saya kemukakan di dua postingan di atas, yaitu koherensi. Koherensi yang bagus hanya dapat diperoleh jika, (1) selisih waktu perekaman citra SAR nya sesingkat mungkin (terutama untuk frekuensi C-Band)  (2) perpendicular baseline lengthnya cukup panjang tapi juga tidak terlalu panjang (100- 1000 m) Kemarin, saya akhirnya mengetahui proses download data SAR yang lengkap dari ESA (akan saya posting tutorialnya di youtube channel geo2004). Dari situ saya memperoleh informasi tentang adanya tandem mission antara satelit ERS-1 dan ERS-2 pada tahun 1995-1997, yang memungkinkan untuk memperoleh data SAR interferometri dengan selisih waktu 1 hari. Saya kemudian mendownload satu pair untuk wilayah Yogyakarta (direkam pada tanggal 21 mei 1996 dan 22 mei 1996), dan memprosesnya di ESA SNAP. ...

This article is a continuation from my previous post about how to perform Wind Direction and Speed Estimation from SAR data. In previous post that you can also read from this blog, I have shown how to directly measure Wind Speed and Wind Direction using ENVISAT-ASAR data. And you can also perform this kind of analysis using other kind SAR Sensors like ALOS PALSAR, Sentinel-1 or ERS.  Now for this post, I will talks about post-processed wind speed and wind direction data generated from Sentinel-1 SAR data. Why Post-Processed ? because ESA already publish wind data from Sentinel-1 into Sentinel-1 OCN Product. So if you are using this OCN product, you dont have to generate Wind Speed and Wind Direction by yourself.  The video tutorial below demonstrate how to get those wind parameters data from Sentinel-1 OCN Product, using ESA-SNAP Software. Hopefully it will find some use to you out there.