Contacts

Identifiers and Keywords

ANZLIC Id

ANZVI0803002576 

Jurisdiction

Victoria 

Topic category

• Imagery base maps earth cover

Resource Constraints

Use limitation

VicMap Digital Image products are provided under the terms and conditions of an annual licence. 

Classification

Unclassified  

Other Dataset Details

Date ( Revision )

2010-07-22

Status

Completed  

Purpose

Vicmap Imagery TM7-2000VI300 will be useful as a backdrop for many data visualisation purposes including map production, spatial and thematic interrogation of vector datasets and in presentation and demonstration material. It will be useable at scales of 1:500, 000 and smaller. Additionally, VicMap Imagery TM7-2000VI300 can be used for visual interpretation of land cover features. Vicmap Imagery TM7-2000VI300 will not be applicable for digital classification purposes, as the digital values have been modified for visual appeal. For any such requirements, the raw component imagery should be used. 

Format

compressed ecw and 8 bit tiff 3 

Supplemental Information

Relationship to other Datasets: VicMap Digital Image TM7-2000 will be an updated and improved version of the existing image catalogue images currently provided in the Corporate Geospatial Data Library. Related Documents: VMDIProductDescript4c.doc. - VicMap Digital Image Product Description 

Maintenance and update frequency

As needed  

Spatial

Spatial representation type

Grid  

Description

General - Victoria 

N

S

E

W

Temporal

Begin date

1999-12-01 

End date

2001-02-28 

Resolution

Horizontal Accuracy

30m  

Quality

Conceptual Consistency

Land cover features across the component images have generally been colour-balanced and matched to each other so that a consistent appearance is achieved across the State. The Vicmap Imagery mosaics have been enhanced to approximate true colour. However, they are still technically false colour representations. In general, forest and tree cover is represented in dark green, irrigated pastures and crops appear as light green, dry pasture and soils vary between red, brown and orange and water is represented as blue. 

Missing Data

Statewide coverage is achieved by mosaicing sixteen Landsat images. 

Attribute Quality

There are no attributes attached to the Vicmap Imagery TM7 2000. All associated information is provided through the standard NRE metadata protocol. Generally, the physical size of the features and the spatial resolution of the ETM+ sensors determine the clarity and sharpness with which those features can be identified. However, the colour contrast within and the colour balance between images can be manipulated to produce a mosaic that is both visually appealing and thematically rich in content. The level of success in achieving this outcome is subjective. 

Positional Accuracy

All component images used in Vicmap Imagery mosaics are georeferenced to the Vicmap Transport - Roads network using an average of twenty evenly spread control points per image. Additionally, component images over the eastern and southern Victorian highlands have been georeferenced using elevation models from the Vicmap Elevation data set. This ensures that Vicmap Imagery mosaics are equally as accurate in high relief terrain as they are on flat terrain. The spatial accuracy of the Vicmap Imagery mosaics is dependant on the accuracy of the Vicmap Transport - Roads network, the accuracy of Vicmap Elevation used in orthorectifications, and the precision with which control points are collected. Individual and average control point root mean square (RMS) errors for each component image are required to be less than or equal to one pixel, or thirty metres. This is usually achieved for all component images with most average control point RMS errors falling under fifteen metres. In general, ninety percent of all Vicmap Transport - Roads should fall within plus or minus 300 metres of Vicmap Imagery. 

Lineage

Description

The process of creating a seamless mosaic from images of different dates requires that the images be enhanced. Image enhancement helps ensure that like features have the same appearances across all images. However, the process may generalise the clarity of some features, as well as increase the sharpness of other features. The process of image enhancement aims to strike a balance between the optimum representation of the major land cover types across the State. 

Statement

Dataset Source: Vicmap Image TM7-2000 is a derived product developed by the Land Information Group. The source Landsat 7 ETM+ imagery is purchased from ACRES. The product name for the imagery purchased from ACRES is Path Image, or Level 1G. The product name represents the level of radiometric and geometric processing performed by ACRES on the data. The Path Image, or Level 1G product, has been radiometrically corrected and resampled to suit geometric correction and registration to a geographic map projection. In all, sixteen images were required to provide statewide coverage of Victoria. VicMap Digital Image TM7-2000 is a static product. Once created it remains unchanged until the next annual update replaces it. The lineage for this product is therefore relatively short. Dataset Originality: Derived 

About the Metadata Record

Metadata identifier

urn:uuid / 6f4ab9b2-66f3-54a5-bc2a-b7eecfceaa48