Interruption du drainage dans ArcGIS 10.6

Question

J'utilise ArcGIS 10.6.1 pour délimiter le réseau de drainage à partir du MNT SRTM de 30 mètres. J'ai utilisé l'outil ArcHydro pour cela. J'ai constaté une interruption dans le réseau de drainage lors de l'utilisation de la projection UTM, mais un drainage continu a été généré avec la projection GCS sur les mêmes données MNT.<\/P> La transformation de projection peut déplacer le raster, mais comment peut-elle changer la valeur des pixels ? Veuillez me faire savoir s'il s'agit d'un bug de la version 10.6.1 car je n'ai pas rencontré ce problème dans la version 9.x.<\/P> Merci.<\/P>

DeanDjokic · Answer

Process of "projecting" (really resampling) DEM can introduce "sinks" into the elevation model.  That would explain the discontinuities you are seeing.  Make sure you fill sinks in the projected DEM before running flow direction and flow accumulation functions.

RupeshSinha · Answer

Thankyou for your reply, I have reproject the dem using both (Bilinear and Cubic) resampling method but still I am getting discontinuous river network.

See the above image where Red line showing the river extracted from GCS dem where there are no discontinuous network while in river extracted from reprojected dem using bilinear and cubic method, there are so many river were discontinued.

GregBarrett2 · Answer

It sounds like your DEM could have been projected using nearest neighbor resampling, which is what you don't want with continuous data like a DEM. See the section titled, "Reprojecting the Right Way: Reprojecting Rasters with ArcToolbox" in this article for more information: https://www.esri.com/about/newsroom/arcuser/looking-good/