Enhancements to Terrain Statistics View

Travis Prescott's Avatar

Travis Prescott

25 Apr, 2018 02:36 PM

I love looking at the terrain statistics profile in CalTopo and include it whenever I send out my emails to trip participants. However, I find people can often be confused by the slope angle histogram, believing it is an indicator of how steep the climb is. Whether I am traversing a steep slope or marching straight up it, CalTopo appropriately shows the same angle (I mean it does say SLOPE angle).

What I'd really like to see added is the same kind of color-coding applied to the distance/elevation trace that shows the steepness of the route, or a view to show the route steepness graph (just the derivative of the distance/elevation graph).

Finally, I like how with the profile view you can move the cursor along the profile and see where it corresponds to on the map. Unfortunately, this capability isn't available in terrain statistics because it fills the window, and instead I have to look at the distance, and then switch back to profile and match it up that way. It would be nice if you could select a statistic on the profile view (with a dropdown) so that you could see the statistic information and easily be able to pinpoint it on the map. I would use this for zeroing in on steep slopes or steep sections of the route (assuming my idea were implemented) so I could potentially re-route.

  1. Support Staff 1 Posted by matt on 01 May, 2018 05:00 PM

    matt's Avatar

    Sorry, your message got marked as spam for some reason.

    It's definitely something that's under consideration, in addition to grade (ie %), since a lot of people seem to think more in percent than degrees when looking at travel routes. Unfortunately it's a question of development resources, and I have some large high-priority projects baking at the moment. On the UI front, it's a little tricky since 1) coloring the actual profile line would require changing the color scheme, as the white-green color I use for flat wouldn't show up well and 2) it doesn't apply to polygon interiors, so I'd need a different set of terrain statistics charts for polygon interiors vs lines.

    The smaller profile box uses Google's elevation data rather than my in-house data, in order to give people an option that works globally. That also means I can't easily generate terrain statistics. If/when I develop a global elevation datasource, I'd be able to add more terrain data to the small profile dialog. However for your described use case, hopefully the slope angle shading layer should help fill that role.

  2. 2 Posted by Keith D. on 01 May, 2018 07:40 PM

    Keith D.'s Avatar

    Hey Travis,

    I have an Excel workbook (attached) that pretty much does what you've described (I think). It works with data exported from Caltopo.

    A small amount of setup is required. First, in Caltopo go to the Terrain Profile and choose to export as a CSV. Open this up in Excel, and paste the contents into cell A3 in the Raw_Data sheet of Terrain_Profile_Plotter.xlsm.

    Next, make sure the formulas in columns L through O extend far enough down for the amount of data that was pasted. If you want to label any points, add the text to column P.

    The other tab contains charts that are already associated with the information in columns L (mileage) and M (elevation). You may need to adjust the parameters of the charts so that all the rows of data are included. You could create your own chart from scratch as well...it just needs to be the "XY scatter" type.

    Now for the fun part! Select one of the charts and press either of the buttons. After accepting any security warnings, it will color code every point in the chart according to either grade or landcover.

    If you run into bugs....you're on your own as I'm not much of a developer and there is no error-recovery or other such sophistication built in. Save your work before pressing the buttons! That said, you can view the code yourself and it should be pretty self-evident what's going on if you know any VBA. Basically, it just loops through every point in the chart and offsets to the column containing grade or landcover, then turns those values into pre-configured colors before going to the next point.

  3. Support Staff 3 Posted by matt on 01 May, 2018 10:14 PM

    matt's Avatar

    Thanks Keith. I should note that the CSV profile export requires a pro subscription, it's not available as part of the free site.

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