2005 Statewide Elevation
The 2005 Elevation Project included delivery of two products: a Digital Surface Model (DSM) and a Digital Elevation Model (DEM).
The DSM is a 5-foot spacing full surface model with trees and buildings. The DEM is a near bare earth model. Both are tiled to
4000x4000 feet, and cover the entire state.
The surface was autocorrelated from two ADS40 black and white sensors. The near bare
earth was also automatically generated, and has a few issues with buildings and spurious cones and holes.
The DEM will hold 10-foot contours "as-is", and may be able to hold 2-foot contours with
confirmation and breaklines from stereo pairs (which are available from the acquisition vendor,
EarthData, for a fee).
Availability
1. Contact your county emergency management agency (
click here for a list of recipients).
2. Download the files for free from the
Indiana Spatial Data Portal.
3. Purchase individual counties on disk from the
IGIC online store.
4. For information on purchasing statewide sets, contact the IGIC offices at
317.234.2924 or
info@igic.org.
Resolution: 1- and 2-meter post spacing (variable based on terrain)
Projection: State Plane coordinates, Zone 16, NAD83/1988 adjustment
Data Format: Imagine .IMG Format
Delivery Method: one set on external hard drive and one set on DVD delivered to State; one individual
county set on DVD delivered to each county. Using the ISTAR processing system, we are able to generate an
accurate, high resolution digital surface model by auto-correlation of the abundant stereoscopic imagery.
Using the acquired digital imagery and ISTAR work flow, an automated
digital surface model (DSM) is generated.
This process provides three key advantages advantages: 1.) Known accuracy, 2.) Cost effectiveness, and 3.) Consistent,
seamless and current.
Each pixel location is measured multiple times resulting in a
much higher level of horizontal and vertical accuracy when
compared to the traditional film/scanning approach. The ISTAR
processing system computes the X,Y,Z value for each DSM post
utilizing every stereo angle collected from the data. The
final DSM generated with the ISTAR process is a “reflective surface
DEM," providing elevation data on above-ground features
including buildings, trees and vegetation. This DSM is used to
orthorectify the raw ADS40 imagery.
Resolution: 1 and 2 meter post spacing (variable based on terrain)
Projection: State Plane coordinates, Zone 16, NAD83/1988 adjustment
Data Format: Imagine .IMG Format
Delivery Method: one set on external hard drive and one set on DVD delivered to State; one individual
county set on DVD delivered to each county. The Digital Surface Model (DSM) is processed to a “near bareground”
DEM, using tools that are also used for LIDAR reflective surface
DEM editing. The DEM is perfectly co-registered with the
orthophotography products. This product is suitable for a variety
of applications, including:
- orthorectification of subsequent aerial imagery done by any jurisdiction (i.e., future orthophotography
and GIS projects will “fit” together)
- automatic extraction of 5-foot contours
- statewide 6-inch and 1-foot resolution orthophotography will support accurate two-foot contours with
further processing (not a delivery of the 2005 Orthophotography Project)
All DSM and DEM products share a common control network. Known accuracy allows for enhancements. With further
processing, break lines can be compiled from stereo pairs to supplement mass points.