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Home - General / All posts - Filling sinks in LIDAR using M9
drtees30 post(s)
#26-Sep-18 21:15

I probably already know the answer to this question, but here it is anyway. I have a large LIDAR data set that I need to use to create a watershed map. In M8, the process involves filling sinks in the LIDAR data before calculating flow paths and watershed boundaries. The data set I am using now is of much higher resolution than older LIDAR data I have used in the past. Calculating watersheds using the older data was very quick (comparatively). The newer data, however, can take a very long time to fill sinks and create watersheds. The data set I am working with right now ran for more than 110 hours before routine office computer maintenance killed the job. I am not looking forward to another drawn-out analysis of this data.

My question is whether M9 has a similar function to fill sinks as M8? I feel that utilization of CUDA should significantly speed up the process of filling the sinks in the data.

General information on my computer:

Dell Precision Tower 5810 with an Intel Xeon processor running at 3.1 GHz, 16 GB RAM, 256 GB SSD drive, NVidia Quadro K620 graphics card. Manifold V8 Build 8.0.30.0. Manifold V9 Build 9.0.168.2.

I appreciate any help!

tjhb

8,280 post(s)
#27-Sep-18 01:18

Not yet in Manifold 9, as you have no doubt correctly guessed.

I don't think the implementation in Manifold 8 is well adapted for the sort of huge DEMs we have now.

It could be worthwhile saying exactly what you will need in the medium to long term, and sending it in as a suggestion.

In the meantime, is processing the dataset in 8 as overlapping tiles an option?

ColinD


1,874 post(s)
#27-Sep-18 11:25

I use SAGA GIS for this, there is a module that is multi-threaded and quite fast.


Aussie Nature Shots

drtees30 post(s)
#27-Sep-18 16:39

I know just enough about GIS in general to be dangerous. I usually do not need to process such a large data set. We need to know the relative size of a drainage basin that provides hydrology to wetlands in order to provide a categorization of the wetland for regulatory purposes. In my current project, the wetland is quite large. Hydrology is provided by a stream that has a watershed covering many square miles. I needed to merge two different LIDAR files in order to encompass the entire watershed upstream of the wetland.

Tiles seems to be a "thing" in M9, based on the functions I have seen available. I will admit my ignorance of what constitutes a tile (time permitting, I will begin my study of the concept). I have no idea how to deal with tiles in M8 or how to set up the data set to be processed in such a manner. I did restart the process of filling sinks in the data set, but this time used the Transform Surface function "fillsinks" instead of having the watershed function do it. This process took only 16 hours.

Thank you for the suggestions. I have some reading to do!

vincent

1,719 post(s)
#27-Sep-18 13:20

I use Taudem for all hydrology task. It is free and not a black box. It come as command line tool or a toolbox for ArcGIS. Hundred times faster than M8.

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