06 May 2009

High Accuracy Contours available over SA and NSW

Apogee provides contours up to 1m over parts of South Australia and New-South-Wales derived from our High Resolution Radar Digital Elevation Model.

We automatically derive our contours from our bare-earth digital terrain models (DTMs) and make them available at various intervals, depending on your specific application requirements and the terrain characteristics of your area of interest. Our contour generation methodology is well-designed, thoroughly tested, and passed through a strict quality control regimen using ISO 9001 IFSAR data

1m contours generated from 50cm IFSAR Digital Terrain Model over
Hindmarsh Island, South Australia

Key Features of Apogee’s Contour Products
Our precision contour datasets are seamless and:
• feature elevations that are referenced to mean sea level
• undergo a rigorous quality-controlled production methodology to ensure the highest accuracy

Key Applications
• Infrastructure planning
• Mining Exploration
• Agribusiness
• Mapping

50cm Contour draped over high resolution imagery over the Coorong, South Australia

Contour Intervals 

When determining the appropriate contour interval for a particular application, it is important to consider the application for
which contours are needed. Different applications may require different contour intervals. One of the factors to consider is the
slope of the terrain within the area of interest.

According to the National Standard for Spatial Data Accuracy (NSSDA) specification for contours, digital elevation model (DEM)
data can be used to create contour data with an interval approximately 3.25 times the vertical accuracy (RMSE2) of the DEM.

While the published RMSE specification for Apogee’s DEM data is 0.5 meter, the average RMSE is between 0.2 and 0.3 meters.
Accordingly, Apogee’s DEM data can be used to reliably generate contour data with an interval of 1 meter.

While these are commonly accepted industry standards, internal analysis has shown that Apogee’s DTM data (in unobstructed
areas) can produce reliable contour data with an interval of 50 cm.

Data Format

Apogee’s contour data is available in various vector formats including AutoCAD® DXF and ESRI® shapefile. The projection,
datum, and units of measurement for the contour data are specified by the customer and correspond to the projection
information of the DTM used to derive the contour data.