chrischutter

Topo to Raster garbage results

Discussion created by chrischutter on Mar 14, 2012
Latest reply on Mar 15, 2012 by curtvprice
I am trying to run Topo to Raster on contour lines representing water runoff.  First off I had to greatly reduce resolution just to get it to run and once it does the results are garbage.  Reclassifying the result so that the colors break at the contour values shows that it does in fact take the correct value at those contour lines, but between them is some garbage.  Between the 100 and 200 contours it has values below 0!!  Shouldn't it be smart enough to know that is not possible without crossing the 100 and 0 contour?  I have a pretty sound understanding of interpolation but it seems Topo to Raster for Arc10.0 does not.  At several contours, value move in the wrong direction on both sides of the line!  Looking at the 100 contour I have values greater than 100 on the side closer to the 0 contour, while on the side closer to the 200 contour I have values lower than 100.  Of course the values then magically cross the invisible 100 contour again before actually getting to the next contour line.  If this tool is so broken is there another means to turn contours into a raster?  Looking at it closely the results seem worst at areas where a contour of one value neighbors itself which is bound to happen on all ridges and valleys in the data.  Anyone know why it is doing this and how to make it stop?  Is there an option to prevent Arc from apparently assuming the contour dataset is incomplete and it can feel free to add new ones?  If a pixel falls between 100 and 200 contour lines it should be really easy to not allow it to have a value of -77!

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