Roughness Area Attributes

TotoroTotoro Global Mapper UserPosts: 18
edited March 2012 in Vector Data
I have tried to assign roughness shapes roughness values for the inside only, since I see no reason why the outside should ever be assigned a value when it itself is inside a large shape with it's own "default" roughness. At least this is the way I have seen most roughness shape maps defined.

I used the RV attribute and export to Map format and I can import the map into WAsP with no major errors. It does however warn of crosspoints, which I assume is due to the roughness and elevation lines crossing. I do not know how to avoid this, but it seems to not affect the results so I have ignored it.

However, I would like to verify that when I have assigned an RV attribute to an area, it does in fact only assign it to the inside. The reason I want to verify this is that when I open an area in WAsP, it defines the area as having both an inside value and an outside value equal to the RV value. Shouldn't it only be assigned to the inside? Shouldn't the outside value be empty? How can I make it so it is?

Comments

  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited November 2011
    The WAsP .map format requires the assignment of both a to-the-right and to-the-left roughness value for roughness areas, although really only whichever of those is inside makes sense and that should really be the only one used. I think whichever value corresponds to outside of the area will be ignored since there should be another area with a valid roughness value covering there, at least that is how I would make it work if I developed WAsP.

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Support
    gmsupport@bluemarblegeo.com
  • TotoroTotoro Global Mapper User Posts: 18
    edited November 2011
    Thanks for the reply.

    The problems seem to stem from the fact that there are roughness areas inside other roughness areas. One would think that this would not be a problem, but since the larger roughness area has a value for the inside and the smaller a value for the outside, then when these collide, it causes problems it seems. Also, sometimes, when the areas share a border the "outside" becomes ambiguous at best.

    Example: An island with a beach and a part of the shoreline which has no beach and instead goes straight to forest. The forest shape has a value for its inside. The beach does too. The water as well. All well so far. The problems start when the water has to define a value for what is "outside" it and this does not match the value for "outside" the beach and "inside" the forest.

    I love global mapper, but I am starting to dislike WAsP with a vengence. I have more than 45000 crosspoints...enough said...
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited November 2011
    Yikes, that does sound like a heck of a problem! I do remember some problems with WAsP and areas with islands/holes. We are hoping to improve the built-in roughness handling in Global Mapper in the near future to make interaction with WAsP and other wind applications much more seamless, so hopefully things like this will be much easier to deal with in the not too distance future.

    Thanks,

    Mike
    Global Mapper Support
    gmsupport@bluemarblegeo.com
    http://www.bluemarblegeo.com
  • GreenkoGreenko Global Mapper User Posts: 7
    edited February 2012
    Hi Mike,

    I am finding some difficulty in preparing a roughness map from google earth snapshot. Could you please guide me with the steps to be followed. Also request you to kindly explain various other methods used for creating a roughness map.

    Is there any online satellite data available for roughness, so that we can generate the roughness contours out of it and then export that into map format.

    Thanks and Regards,

    Sri Priyanka
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2012
    Sri,

    I'm not sure how you could possibly create one from a Google Earth snapshot (i.e. imagery), but in the latest v13 builds there is built-in access to land cover layers on the File->Download Online Imagery/Data menu command. You can pull in land cover for your area, then right-click on that in the Control Center and select to create a roughness grid (including areas). You can then export that to a Wasp.map file.

    I have placed a new build at http://www.globalmapper.com/global_mapper13.zip with the latest changes for you to try. Simply download that file and extract the contents into your existing v13.xx installation folder to give it a try. If you are using the 64-bit v13 version there is a new build at http://www.globalmapper.com/global_mapper13_64bit.zip .

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • GreenkoGreenko Global Mapper User Posts: 7
    edited March 2012
    Dear Mike,

    Thank you very much for your quick response.
    We are presently working with India projects, so the Land cover maps suitable from available options is VCF Tree Cover 500m resolution. Could you please provide me with the literature related to it and correct me if i am selecting a wrong option for land cover maps.

    Thanks and Regards,

    Sri Priyanka.





    Sri,

    I'm not sure how you could possibly create one from a Google Earth snapshot (i.e. imagery), but in the latest v13 builds there is built-in access to land cover layers on the File->Download Online Imagery/Data menu command. You can pull in land cover for your area, then right-click on that in the Control Center and select to create a roughness grid (including areas). You can then export that to a Wasp.map file.

    I have placed a new build at http://www.globalmapper.com/global_mapper13.zip with the latest changes for you to try. Simply download that file and extract the contents into your existing v13.xx installation folder to give it a try. If you are using the 64-bit v13 version there is a new build at http://www.globalmapper.com/global_mapper13_64bit.zip .

    Let me know if I can be of further assistance.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2012
    That is the only one there that covers India, although it is admittedly the least useful of the sources. If anyone knows of better land cover for India that would be useful.

    That data source comes from the MODIS VCF data. See http://www.glcf.umd.edu/data/vcf/ for details.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • GreenkoGreenko Global Mapper User Posts: 7
    edited March 2012
    Dear Mike,

    Thanks. I was able to download the roughness data from VCF Worldwide.
    I have one more error in one of our projects. Our project is falling in two different UTM (Universal Transverse Mercator) zones i.e 43 P and 44 P. In order to create the Elevation Grid for the same from SRTM data i am unable to create XYZ grid for both the zones in a single file. We need this xyz grid as orography file for wind analysis in Meteodyn.

    Could you please help me out of this?

    Thanks and Regards,

    Sri Priyanka.

    That is the only one there that covers India, although it is admittedly the least useful of the sources. If anyone knows of better land cover for India that would be useful.

    That data source comes from the MODIS VCF data. See http://www.glcf.umd.edu/data/vcf/ for details.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2012
    Sri,

    You should be able to setup a UTM projection on the Projection tab of the Configuration dialog and just choose one of the 2 zones that you are working in, then export your entire data set to a XYZ file. The coordinates will extend outside the selected zone and be continuous coordinates for that zone. I wouldn't try to go more than one zone away from the best fit one as UTM gets very bad when you get far from the projection center, but for just one zone away you should be ok.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • GreenkoGreenko Global Mapper User Posts: 7
    edited March 2012
    Dear Mike,

    Could you please elaborate. I tried doing this but the coordinates didnt extend outside.

    Regards,

    Priyanka.

    Sri,

    You should be able to setup a UTM projection on the Projection tab of the Configuration dialog and just choose one of the 2 zones that you are working in, then export your entire data set to a XYZ file. The coordinates will extend outside the selected zone and be continuous coordinates for that zone. I wouldn't try to go more than one zone away from the best fit one as UTM gets very bad when you get far from the projection center, but for just one zone away you should be ok.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2012
    Did they just stop at the UTM zone edge? Was that in Global Mapper or in the other application? While Global Mapper supports data crossing UTM zones without problems some applications don't like that.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • GreenkoGreenko Global Mapper User Posts: 7
    edited March 2012
    Dear Mike,

    I am attaching a jpg file which contains my project boundary and the areas which are falling in different zones are marked. The boundary coordinates are also specified. Could you please suggest me the procedure to be followed for creating xyz elevation grid from SRTM data.

    Thanks and Regards,

    Sri Priyanka.








    Did they just stop at the UTM zone edge? Was that in Global Mapper or in the other application? While Global Mapper supports data crossing UTM zones without problems some applications don't like that.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
  • global_mapperglobal_mapper Administrator Posts: 17,238
    edited March 2012
    Just load your boundary Shape, then use the File->Download Online Imagery/Data menu command to pull down SRTM tiles for that area, then use File->Export Elevation Data to export that inside the desired bounds to a XYZ Grid format file.

    Thanks,

    Mike
    Global Mapper Guru
    gmsupport@bluemarblegeo.com
    http://www.globalmapper.com
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