Title

Upper Barwon River DEM Diff 

Time period

2020-06-122020-06-12 

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

DEM difference analysis was conducted on a per-river basis. The Difference DEM was generated by subtracting the existing 2009-10 DEM surface from the new DEM surface. This required the transformation of the 2009 data from GDA94 to GDA2020. The level of the old surface was vertically adjusted (co-registered) to the level of the new surface by comparing heights at selected sites representing unchanged areas. At least three unchanged co-registration sites per river were used. 

Classification

Unclassified  

Attribute Quality

Positional Accuracy

Conceptual Consistency

Comments

The desired level of co-registration (at the 3 co-registration sites) was specified as 0.1m. Despite achieving this level of co-registration, there can be variability in the level of surface co-registration across the broader river AOI. Surface co-registration variability will manifest in the DEM difference product as areas of changed surface level. There are several possible underlying reasons for differences in the DEM surface including innacuracies in either of the source DEMs or real surface change. Each river Difference DEM needs to be assessed at the local site level to ascertain whether surface differences are real, an artefact of either source dataset or the result of a problem with the co-registration process. 

Missing Data

Comments

Complete for river AOI. 

Excess Data

Platform Type

Aerial  

Assembly

Single  

Tile Size

1 km  

Raster Type

Digital Height Model  

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

Orthorectified  

Platform Name

Fixed Wing Aircraft