Title

Mallee CMA - DTM 

Time period

2019-02-112019-02-14 

Horizontal Accuracy

0.3m  

Vertical Accuracy

0.2m  

Code

MGA Zone 54 GDA2020 

Title

ESRI Ascii 

Topic category

• Elevation

Use limitation

General 

Classification

Unclassified  

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. 

Classification

Unclassified  

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

Platform Type

Aerial  

Assembly

Mosaic  

Tile Size

1 km  

Raster Type

DEM  

X Pixel Resolution (cm)

1cm  

Y Pixel Resolution (cm)

1cm  

Seamlessness

Full  

Number of Bands

1 

Band List

1  

Resampling Kernel

Nearest Neighbour  

Rectification Type

Not Entered  

Platform Name

Fixed Wing Aircraft  

DEM Creator

Supplier