Title

Horsham - DEM 

Resource Type

Dataset  

Spatial representation type

Grid  

Horizontal Accuracy

0.3m  

Code

MGA Zone 54 GDA94 

 

Title

ESRI Ascii 

Topic category

• Elevation

Use limitation

General 

Classification

Unclassified  

Description

ArcGIS 9.2 Terrain Grids were derived using the Natural Neighbor interpolation from points representing Classes 2. This method uses the closest triangles and applies weights to the proportionate areas from the grid cell centroid to interpolate the value. It uses known elevation data, it does not make any predictions regarding the surface and accurately depicts existing troughs and peaks in the data and supports irregular point spacing, which suits the nature LiDAR data. Hydro Flattening process was undertaken on the data, during editing of the LiDAR point cloud 2D hydro boundaries of water bodies were manually digitized. The hydro boundary polygons were digitized from the LiDAR intensity imagery and the LiDAR surface model, these results were verified against aerial imagery. The hydro boundaries were then draped onto LASD dataset and the minimum Z for each hydro polygon extracted. Heighted hydro polygons then incorporated into LASD dataset. LASD to DEM grid process generation using hydro flattened polygons. The Horsham project are was mereged with the 2011-12 Flood Plains LiDAR Stage 2- Wimmera CMA project. The a point cloud was used in the DEM merge process, a minimum of 50m overlap was used between the projects, cut lines were derived to avoid areas of change in the overlap area. The Ground and non ground data was reclassified in the overlap area to avoid any `noise¿ between merged datasets. The merged DEM's were created using the new merged point cloud data. Breaklines such as the water polygons digitized during the LiDAR editing stages of the Hydro Flattening were used. 

Classification

Unclassified