Door Symbols For Prefire plans
February 24 2009 |
I am working on creating prefire plans in our GIS. I have run into a challenge with representing interior and exterior door point symbols I hope you can help with.
I have scanned and georeferenced building interior floor plan blueprints, and digitized building footprint polygon features, interior wall line features, and room polygon features over the scanned blueprints. The rooms are symbolized by various colors and classified by room use (office, warehouse, HAZMAT storage etc.)
The challenge I need to work through is how to represent the door point features. I need to somehow mask the underlying line feature for walls while maintaining the underlying polygon feature color symbology for the room use classification. If I just make a white rectangular mask for the door opening the room symbology is also masked.
Mapping Center Answer:
The answer to your solution lies in Variable Depth Masking. Variable Depth Masking is a drawing technique for hiding parts of one or more layers. In essence, you first create a polygon "mask layer" based on the layer that you want to "knock out" below it. Then you use that mask layer to mask out some feature symbology to make the map more readable. With Variable Depth Masking, only some layers are hidden by the masks. So, for example, when using a mask for your door points, those sections of wall lines behind them are hidden but the polygon colors appearing behind the wall lines layer are still visible.
In ArcToolbox, there is a Cartography Toolbox that contains the Masking toolset. To create masks for the points layer, use the tool that creates mask polygons at a specified distance and shape around the features in the input layer. This is the Feature Outline Masks Tool.
Click the Input Layer dropdown arrow and select the door points layer. Then type the name and location for the Output Feature Class. Type a value in the Margin parameter – this is the distance around the points that you want to mask out. Click the Mask kind dropdown arrow to select an outline method. It won't make much difference for poitns, but if you happened to use this to knock out behind something else, like text, using Convex Hull (the recommended method) represents the shape of the text, but not the internal holes. Now click OK.
For Variable Depth Masking to work, the mask layer must be in the data frame. Right-click the data frame in the table of contents and click Advanced Drawing Options. Check "Draw using masking options specified below". You would uncheck this if you wanted to turn masking off. Click the layer to use as a mask in the Masking Layers list – yours would be the point layer mask layer you just created. Then check the layers you want affected by the mask – you would choose the walls line layer. Click OK. At this point turn off but don’t remove the mask layer.
You should now see the results you are looking for!
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