Frequently Asked Questions

MIKE 21

Please do not hesitate to e-mail us if you have questions and/or answers yourself: mike@dhigroup.com.


 

    Entered: 2018-11-9
  • Question:

    MIKE 21: How can I use a polygon layer to exclude buildings from my flexible mesh?


    Answer:

    If you have a polygon shape file, you can convert it to a *.xyz file, which can be imported in the Mesh Generator.


    To achieve this, open the MIKE Zero Toolbox, and select the tool Shp2Xyz, which is available under GIS:

     Buildings_1.png

     

    From this tool, you can select your input shape file, and specify the type of input data to be converted (for buildings, the type should be polygon):

     Buildings_2.png

     

    After specifying the output *.xyz file name, you can execute the tool, which creates a text file containing four columns: X coordinate, Y coordinate, Z elevation, connectivity.


    From the Mesh Generator, you can now import this text file, from the Data \ Import boundary… menu. You will be prompted to specify the properties of the *.xyz file: select the format X, Y, Z and Connectivity, and make sure the projection and units are correct. Select polygons to be excluded from the mesh.

     Buildings_3.png

     

    Polygons are then imported in the Mesh Generator and can be used to build the new mesh. Each polygon is imported with a polygon marker that state it is to be excluded from the mesh.

      

    Buildings_4.png

    Note that polygons are imported with the exact same shape as in the shape file. If some polygons are very detailed or if some are very close to each other, you may end up with a mesh containing unexpected odd elements. Besides, if the shape file contains overlapping polygons, the Mesh Generator may not be able to generate the mesh, and the problem will need to be fixed manually. Therefore, it may be useful to preprocess and validate the shape file before importing it.