Slope degree depending on direction

AquasoliAquasoli Global Mapper UserPosts: 11

I have a question, which I gave some thought but so far have not been able to figure out, whether current GM functionality allows me to do that.

Basically I am trying to separate the slope degree display into different directions. Any slope has usually two aspects: North-East, N-W, S-E, S-W (except for perfect N, E, S, W-slopes). Is it possible, to somehow separate these aspects? So basically I would like to have one view, in which I can see only the respective slope degree in southern direction, then one for E, W, N. The coloring should be like for the normal slope shader with the different thresholds defined.

The point is, that one point may be slope in S-direction 5° and at the same time 10° in W. However, the normal slope shader option only gives the "aggregate" or actual slope of the section. It is not possible, to separate the two.

I hope I am making myself clear. In the end, I want to have a slope analysis like the ones that can already be created using the shader options, but separated into the 4 different directions.




  • samknightsamknight BMG Staff Posts: 80
    Hi Jakob, are you aware of the Slope Direction Shader in the Shader drop down?  This shades the terrain by horizontal direction of the terrain for each of the compass directions.  You can control the colors displayed via the Configuration>Shader Options dialog.  This interpolates the color based on compass direction of slope between the chosen colors.  Let me know if I have misunderstood what you are trying to accomplish.

    Sam Knight
    Director of Product Management
  • AquasoliAquasoli Global Mapper User Posts: 11
    Hi Sam,

    there has been a quite (quite) big time lag here, but in regards to your above answer, actually my question at the time was not really answered.

    I have prepared two more screenshots from a current project, which might help to illustrate what I am looking for. Basically we are installing large scale solar systems and in such case the North- and South-facing slopes are very important factors. Apart from the shadowing effect (I have some other questions I sent you guys about this right now) it is also about the installation of the system. I am basically using the topo-analysis functions of GM to give me a better idea of how long I need to make the poles that support the system. As the poles are usually installed in two rows, one front and one back pole, I need to now the N-S slope of the ground in order to now how long I need to make those poles. The E-W inclination is only secondary in that regard, as the structure on top can be adjusted accordingly.

    What I am currently doing is what you can see in the screenshot, which is basically just creating section views in NS-direction to check the change in inclination. This is fine, but it is time consuming because I need to analyse each section individually and arbitrary because I have to estimate myself based on the contours which areas I best divide. So if I could color the area only based on the northern slope aspect I would have a very clear picture.

    As an example, the section 1 runs through an embankment of the site, which has an inclination of about 29° in EW direction, but in NS direction it is almost flat.

    The slope direction function does not really help me here either, because it basically colors everything that is facing even slightly in northern direction, but it does not tell me how much.

    So maybe with this information you can let me know one more time if the existing functionality of GM may be able to do something or if you might be able to add something like this without too much effort.

    Thanks and regards, Jakob

  • kfroesekfroese Geotechnical Engineer Posts: 149Trusted User
    If you export your surface to a Float/Grid file, there is a check box that will allow you to export "Slope Direction" instead of elevation. If you import that file back in, you'll have a surface where "elevation" is actually slope direction. You may then be able to use "Create Area Features from Equal Values..." and then a filter to find areas facing predominantly one direction. I haven't tried this myself with a sample data set to see if it would work but it might get you on the right path.
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