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DTM editing

PeterMichalak

Dear,

I'm having problems editing my DTM (Tiff format). I need to assign a certain elevation for a river. Is it possible to draw a polygon covering the river, with a certain elevation value and somehow merge it with the DTM raster? Or is there an easier way to cope with it?

Thanks for your help

Peter

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JimHall

The problem may be in your not setting the "snap raster" for your outputs. Set environment setting to your original raster for all your steps.

PeterMichalak

Right,

I have managed to sort the problem out, if anyone has the same issue I'd suggest the following:

1) Draw a shp representing river > Convert shp to Raster with a predefined value of 87 (elevation)

2) Cut the DTM raster using Mask tool in Image Analysis Window

3) Clip 2 rasters using Mosaic to New Raster Tool

4) I've used SetNull tool to Set Null values for the background

Everyting worked fine except I've got small gaps where there 2 rasters meet (after using Mosaic to New Raster):

I'm not sure what have caused this, probably the fact that rasters were cut using polygon which represents irregular shp, comparing to raster's regular cell grid. Anyway I'm not sure how to get rid of these gaps, I have tried Snap to Raster setting but did not help.

Any suggestions?

Regards,

Peter

PeterMichalak

Ian,

Thanks for your answer. I have installed ArcHydro and tried to use Level DEM tool but...it did not work

I have drawn a polygon around river and added a field representing its constant elevation. Then I used Level DEM tool but it did not changed the input DTM at all (or actually changed it in a way I cannot really understand).

Is there something I'm doing wrong here?

Cheers,

Peter

IanMurray

Peter,

Have you looked at the ArcHydro downloadable extension? It should allow you to burn streams into your DTM, overriding the existing pixel values.

Arc Hydro Overview | ArcGIS Resource Center‌

Problems with Burn Stream slope and DEM Reconditioning‌

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=1&ved=0CB0QFjAA&url=http%3A%2F%2Fdownloads.esri.com%2…

Hope this gets you in the right direction

‌

PeterMichalak

Thanks for you answer 808 707

Yes the river has got a constant elevation. However a buffer would not be accurate enough, I need to set the river boundaries more accurately. The ideal way would be to draw a polygon representing the river set a 'z value' to the polygon and then convert it to raster and somehow superseed DTM, information for river areas with constant value.

Any help appreciated,

Cheers,

Peter

808707

Does the river change elevation or is it the same for the entire length?

Have a look at raster calculator.

You could buffer your river to the desired pixel width and elevation

Convert this to a raster then subtract the river raster from the DTM within Raster calculator.

Hope this points you in the right direction.

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