ArcGis - Week Three 13.10.16

    GIS - Geographical Information System

     

    ArcGIS is used for working with maps and geographical data. It main purpose is to create maps, compiling geographic data and analysing this information. ArcGIS includes the following software:

     

    • ArcReader
    • Arc Catalogue (file viewing platform)
    • ArcScene
    • ArcGIS for desktop

    Digimap

     

    The data necessary for working in GIS can be retrieved from Digimap: Ordnance Survey Maps and data. This data is used as a base for making 3D mdels and surface analysis. The data downloaded for this tutorial includes Topography, and building heights, OS street View/ Land and Height Data, OS Terrain 5 Contours and OS Terrain 5 DTM (DIgital Terrain Model). The DTM file is used for the base to make the topological surface model in GIS.

     

    DTM > ASC file

    Contours > SHAPE file

    Street View > .tiff file

    Building heights/ topography > File Geotable Data

    • Digimap data download
    • Digimap download for Strand to use in ArcGIS

    ArcScene (Preparing OS Terrain 5 DTM Raster Data to View as 3D model)

     

    1. Open ArcScene and right click on 'layers properties' > 'vertical exaggeration' box and select an arbitrary number (here I have used 5).
    2. Add elevation raster layer by choosing 'Folder connection' choose the digimap folder and drag and drop the raster file into the scene. Double click on the new raster layer and adjust the base height to 'Float on a custom surface' and alter the X & Y cell-size to match the original surface (5).
    3. The rendering tab can help with the viewing results in the scene. Here, the drawing priority has been adjusted to '2'.
    4. The symbology tab can be used to change the colour ramp to something suitable for the elevation.
    5. Geo-referenced data can be draped over the surface. I have added the OS street view to the scene. The same steps as above were used to attach the OS street view to the topographical surface. The raster resolution was left as its default settings.
    6. Before saving the map, the 'store relative path-names to data sources' should be checked in 'scene document properties.
    • Vertical Exaggeration Setting
    • Drag and drop Raster Elevation from Terrain 5 DTM Data
    • Drape OS Street View on to surface
    • Adjust rendering priority for better viewing results
    • Add building heights

    ArcScene (Preparing OS Building Heights)

     

    1. Drag the building height digimap data into ArcScene.
    2. Go to 'Base Heights' Tab and adjust as previous steps to match elevation data.
    3. In the 'Extrusion Tab' check 'Extrude features' and in the Extrusion value box, enter [RelH2]*1 which means the relative height from ground level to base of the roof.