Title

Glenelg Hopkins CMA - Difference DTM 

Time period

2019-03-132019-03-16 

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

DTM difference analysis was conducted on a grouped process. The Difference DTM was generated by subtracting the existing 2009-10 DTM surface from the new DTM 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 four unchanged co-registration sites per group of rivers were used. 

Classification

Unclassified  

Attribute Quality

Positional Accuracy

Conceptual Consistency

Comments

The desired level of co-registration (at the 4-11 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 DTM difference product as areas of changed surface level. There are several possible underlying reasons for differences in the DTM surface including innacuracies in either of the source DTMs or real surface change. Each river Difference DTM 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 AOIs within the Glenelg Hopkins CMA. 

Excess Data

Platform Type

Aerial  

Assembly

Single  

Tile Size

1 km  

Raster Type

Difference Raster  

X Pixel Resolution (cm)

1cm  

Y Pixel Resolution (cm)

1cm  

Seamlessness

Not Entered  

Number of Bands

0 

Band List

Not Entered  

Resampling Kernel

Not Entered  

Rectification Type

Not Entered  

Platform Name

Not Entered