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Onscreen Digitizing   

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Preparatory Phase
P3DM supplies
Assembling the "blank"
Depicting info
Transposing info
Data Extraction
Digital Photography
On-screen Digitizing
GIS processing
Map Production (1)
Map Production (2)
Data validation
Handing Over
P3DM and PM&E

Community Participation and Geographic Information Systems

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This page was
last updated on
June 29, 2010




Once you have taken all images and safely stored them on a computer, you may use them independently or merge them using appropriate software.

Merging techniques are generally well described in the manuals accompanying the software provided together with professional digital cameras.

The saved image(s) are now in raster image format ready for digital extraction, correction and geo-referencing. This requires their conversion to vector format through onscreen digitizing.  This requires their conversion to vector format through onscreen digitizing.

Onscreen digitizing, as opposed to tablet digitizing, is increasingly becoming the most popular means of creating GIS spatially organized data.

On-screen digitizing captures data from digital images or scanned maps by using the mouse instead of the cursor. This allows for creating map layers by adding labels during tracing. While the features are still manually traced, and provided images have been taken at high resolution, on-screen digitizing grants a higher level of accuracy because the operator can use the zoom facility. In addition, on-screen digitizing allows for editing features when enough information is available from the image.


A raster image file is generally defined as a rectangular array of regularly sampled values, known as pixels. Each pixel (picture element) has one or more numbers associated with it, generally specifying a color, which the pixel should be displayed in.


A vector image is generated through a sequence of commands or mathematical statements that place lines and shapes in a given two-dimensional or three-dimensional space.


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