Introduction

There are many ways to collect data. Currently, there are two main ways to collect initial building footprint, sidewalk, and street data. First, you start with an aerial or GIS data. Secondly, you collect photographs in the field.

GIS/ AUTOCAD DATA

Already having your data in AutoCAD and GIS saves you a lot of time. If you are working on a project for the North Shore area just outside Chicago, check the GIS Consortium. If you do not have access to electronic data, you are going to have to build it yourself. Many municipalities do not have or maintain data in a GIS because they can not afford the initial costs of digitizing the information. If you have to start from scratch, one way is to digitize the maps using AutoCAD, export as a DXF into your 3D modeling package, or import into a GIS. You can also export out of GIS into AutoCAD using the Arc to CAD extension. Another method is to trace the sidewalks and parcels on the aerial photograph in Adobe Illustrator. You can export the parcels to a 3D modeling package and extrude the parcels. Consider doing a thorough job in AutoCAD and sell or give your maps and layers to the municipality.

I do not suggest extruding lines in AutoCAD and importing an entire model into a 3D Modeling package. You will ultimately want to keep all objects within the scene as separate objects if you are using a modeling package such as 3D Studio or Maya. If you use MultiGen, an entire flight file can be imported into YG. AutoCAD adds extra polygons; use AutoCAD to get a precise base map of the location and export it. Use it as a guide in your modeling package, but do not use the objects created in AutoCAD in the CAVE. You will find that your models are polygon heavy and you will end up sacrificing frame rate.