Topo to raster output extent

[francescarusso]

Hi all,

A while ago I asked how  I could interpolate some contour lines (bathy and isopachs) with ArcGIS 10.2 Spatial Analyst and I have been told to use the tool Topo to raster which did the job! I have just a concern about what I got.

basically I have a cable route and the bathy contour lines as well as the ispoachs lines; Once I use topo to raster it looks a bit odd that they cover a huge area outside of the cable corridor and I d not know if this is due to some parameter that I should have set  or it is like it is.

For instance the screenshot below shows the cable route (in red) where they did the survey. Along that route I have either bathy contour data and isopach lines. Then using topo to raster I get the pic below and I am surprised that they cover a huge area outside the red line.

Do you have any suggestion?

many thanks  and have a nice day,

F

[DanPatterson_Retired]

Unless you went into the Environments tab in the topo to raster tool and explicitly set the analysis 'extent' prior to running the tool, then you will get what arc* feels like or whatever it defaults to at that time.  All tools need some parameters to guide its processing... extent, cell size, snap raster, no data values ... these are some of the overt decisions that must be made prior to using any tool in ArcToolbox.  So begin with setting the analysis extent.

[curtvprice · Accepted solution]

Yes, Topo To Raster is a spline interpolator so it fits a surface through your data and outputs values everywhere in the output extent. This defaults for maximum of inputs for this tool, the help doc defines what "arc* feels like" 🙂 for each tool. 🙂

You may want to clip the output (maybe to a buffer of your cable route) to get the exact surface you want.

Clip—Help | ArcGIS Desktop 

[francescarusso]

Thanks this is also a good idea. I had a go and it looks like is doing my job.

Cheers,

F

[francescarusso]

Thanks a lot