Topo to raster creating "valleys" where the input doesn't suggest it

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01-22-2016 10:35 AM
JúlioLuta
New Contributor III

Hi,

I've been creating some raster from topo files but in some places I get weird valleys where there shouldn't be any.

I've attached two screenshots, one with the inputs I've been using with the tool topotoraster and another trying to explain the problem.

In the picture:

- The two bottom points have the same elevation

- Both the top ones have higher elevation than the bottom ones

- All points have an elevation between the lines that surround them (and these lines have a 1m elevation difference)

- The difference in grey show the valley

- As a result my arcs get slopes where they shouldn't be one (in red)

Not in the picture:

- Bellow that area there is nothing suggesting such a valley

Did this happen to anybody before? What can be making that?

Edit: two more pictures, one with the elevations of the four points. Another with better colors in the terrain, from 87m elevation to 88m, each color representing 10cm.

Cheers,

Júlio

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4 Replies
DanPatterson_Retired
MVP Esteemed Contributor

It is plausable, given the points are at different distances from the lines...but what are the elevations of the points anyway?

JúlioLuta
New Contributor III

I edited my post adding more screenshots.

With that kind of modelling I don't know how much can I trust TopoToRaster. I have counted at least four instances where this "buggy" values appear.

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JúlioLuta
New Contributor III

I'm bumping this thread just to add that I think this result might be caused by the "Drainage enforcement process". At this time I don't have the possibility and time to redo the model and test it. It was unfortunate that I din't notice this detail/option before or, if I did, I didn't correlate it with this "issue". This information might be useful if somebody is noticing the same thing.

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SteveLynch
Esri Regular Contributor

Your Data type parameter is set to Contour, rather change this to SPOT if your primary input = points.Also, have you looked at any of the diagnostic outputs, I see that all these are empty in screenshot 34.

Ie. see Evaluating output in How Topo to Raster works—Help | ArcGIS for Desktop 

-Steve