Mallee CMA - DTM

dataset
Dataset: Mallee CMA - DTM Assembly: Mosaic
 
Citation proposal Citation proposal

Mallee CMA - DTM

Department of Transport and Planning

Description

Title
Mallee CMA - DTM 
Resource Type
Dataset 
 
 

Spatial

Spatial representation type
Grid 
Horizontal Accuracy
0.3m 
Code
MGA Zone 54 GDA2020 
 
 

Format

Title
ESRI Ascii 
 
 

Contacts

  Point of contact

  Custodian

 
 

Keywords

Topic category
  • Elevation
 
 

Resource Constraints

Use limitation
General 
Classification
Unclassified 
 
 

Lineage

Description
The DTM was primarily generated from the point cloud class 2 (ground). Class 9 (water) was also used in the DTM in order to form a continuous surface across the river channel where DTM interpolation could not fill data voids caused by water. The decision to include water points in the DTM was based on the following: - Hydro flattening of the river channel was not undertaken. The hydro flattening would normally infill the river channel area with (flat) surface data, regardless of lidar returns from the water surface. However, without the hydro flattening process, large void spaces would be present in the river channel area if only ground points were used. - Hydro flattening was not undertaken because the process relies on the manual delineation of where the water line finishes and channel bank begins in the point cloud classification stage. For the purposes of the project, it was important for this delineation to be undertaken using the Frontier-SI River Line Toolkit. - Although void areas could have solely been filled in by a TIN interpolation process, the preference was to utilise all available LiDAR returns from the channel area (ie; points classified as water) and then rely on TIN interpolation where no LiDAR points were available. ArcGIS 9.2 Terrain Grids were derived using las2dem. This tool reads LIDAR points from the LAS/LAZ format (or some ASCII formats), triangulates them temporarily into a TIN, and then rasters the TIN onto a DTM. 
 
 

Metadata Constraints Metadata Constraints

Classification
Unclassified 
 
 

Quality

Attribute Quality
Positional Accuracy
Conceptual Consistency
Comments
DTM is absent of excessive triangulation and data voids. In areas beyond the 200m buffer, the LiDAR ground class has not been edited beyond automatic classification and may contain minor surface errors. The DTM is considered accurate inside the River AOI, however outside the AOI, the surface may contain artefacts from uncorrected point cloud classification anomalies. 
 
Missing Data
Comments
Complete for river AOIs within the Mallee CMA 
 
Excess Data
 
 


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