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.