Viewshed problems

jdoujdou Global Mapper UserPosts: 7
edited July 2010 in Technical Support
Hi,

I have just installed software to get an insight of a potential viewshed of a marine based windfarms around a Island. I am using an ASCI file as the map for the Island, however I am not getting any viewshed whenever I place any structure a few meters away from the coast. However, this is working fine when I place a structure in a bay. I tried placing structures on a sister Island but the effect was almost invisible on the other land since the view spread across the water. Is there a way how one could go around this issue? Any help would be appreciated.

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited July 2010
    It sounds like you are placing your transmitter at a location where there is no elevation data, so a view shed isn't generated. I think what you need to do is replace all invalid values in your terrain layer with 0 so there will be valid elevation data there. To do this, simply open the Control Center, select the terrain layer(s), press Options, then go to the Adjust Elevations tab and select the option to replace invalid values with 0.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • jdoujdou Global Mapper User Posts: 7
    edited July 2010
    Yes It worked out perfectly well.
    Thanks

    jdou

    It sounds like you are placing your transmitter at a location where there is no elevation data, so a view shed isn't generated. I think what you need to do is replace all invalid values in your terrain layer with 0 so there will be valid elevation data there. To do this, simply open the Control Center, select the terrain layer(s), press Options, then go to the Adjust Elevations tab and select the option to replace invalid values with 0.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    support@globalmapper.com
  • jdoujdou Global Mapper User Posts: 7
    Hi I have another viewshed problem. I am trying to export a viewshed generated on GM as a KMZ file. I am right clicking on the viewshed generated as a layer and go to layer and Export layer to new file and save as KMZ. The problem is that the image on Google Earth is different from that generated on GM. I've been checking different boxes but keep getting teh same image over and over again. I need the same image. Tried saving as jpg but got the correct image on a white background, which I don't need.
  • bmg_bobbmg_bob Global Mapper Programmer Posts: 2,158
    Hello,

    How are the images different? Can you post a couple of screen captures to illustrate? 

    Cheers,
    Bob
  • jdoujdou Global Mapper User Posts: 7
    attached file with printscreens
  • jdoujdou Global Mapper User Posts: 7
    Hi,
    Can anyone explain why I am getting different images please? I attached printscreen in previous communciation but so far there was no reply.
  • 946946 Global Mapper User Posts: 151Trusted User
    edited April 12
    Hi,
    The area is to complex to draw in GE.
    Try this settings


    Or simplify the shapes prior to export.
    If you load back the kmz file to global mapper I suppose it s OK.

    In the end, if nothing works, do the viewshed directly in Google Earth.




  • jdoujdou Global Mapper User Posts: 7
    Thanks for your reply, however note that the viewshed obtained through GE are no match with those produced by GM and I need an accurate viewshed not an approximate one. Secondly, I've done this process several times before  and exported into GE as KMZ files but never got such a result. However, I will try your suggestion.
  • bmg_bobbmg_bob Global Mapper Programmer Posts: 2,158
    jdou said:
    Can anyone explain why I am getting different images please? I attached printscreen in previous communciation but so far there was no reply.
    Hello,

    If you are not getting a timely response on the forum, you should always feel free to contact Blue Marble Support directly via email (geohelp@bluemarblegeo.com). Please provide a detailed description of your workflow, and sample data that can be used to reproduce your results. Thanks.

    Cheers,
    Bob
  • jdoujdou Global Mapper User Posts: 7
    Tried exporting it  using the above settings but always got the same results. Any other solutions would be most welcome.
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