Is there a written guide on how to create a street map (that could be used for geocoding) from an aerial photo?
Is there a written guide on how to create a street map (that could be used for geocoding) from
an aerial photo?
Mapping Center Answer:
I don’t know of any written guide on specifically on this subject. A personal geodatabase (ArcGIS 9.2) and layer file is enclosed in the ZIP file and it contains an excerpt from an example street centerline feature class that I’ve created (I used it to create the symbolizing cased roads Mapping Center blog entries). It should serve to give you a reasonable idea of the fields that go into such a dataset, as well as some of the values for given kinds of records. I also included a layer file; you’ll need to set the source property to use this excerpted data set to see how some of the fields were used for symbology.
Here are some other resources to check:
- The ArcGIS Address Data Model
- The ArcGIS Transportation Data Model
- In terms of a book, Designing Geodatabases would be good reference as well.
The compilation for the data (from the above link) done in ArcGIS using the Editor and 2m color ortho imagery. The data is geocodable, and also participates in a network dataset.
For digitizing smooth streets with clean intersections I have two tricks:
1. Use the Endpoint Arc Tool when digitizing curved segments of streets. Tip within the trick: you can use this when creating new features or when using the Reshape edit task.
2. Clean intersections can be done by using Snapping, which can sometimes miss and snap to the wrong vertex (but it works at the ArcView license level). To avoid even those problems I build a geometric network (requires ArcEditor or ArcInfo license), and that actually forces proper connectivity as you edit; and is definitely the easy way to do this task. You can build a geometric network for your existing streets and as you edit them the get cleaned up.
That said it took a long time to build this data (800+ hours and I started with some much lower quality data that I improved). The hard part of generalizing this task down to a written document is that many cities and counties ‘do their own thing’. Some are very good, some not quite as good. But even the very good examples vary considerably based on their staff’s philosophies about addresses, cartography, and data management techniques.
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