102 l4 geoinfo raster geoprocessing 03mar13.pptx

7/28/2019 102 L4 GeoInfo Raster Geoprocessing 03Mar13.pptx

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Geo-processing

Geo-processing is a process which turns

geospatial data to useful spatial informationand map to intelligent , dynamic map.


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Raster data were processed separately and usedfor different purposes

Raster Data-Spatio temporal modeling in

environmental application

Vector Data- Digital mapping and resources

inventories


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Scanned Photograph Black & white or color

Remote sensing image

Tiff Scanned Map

Thematic Map

Raster Data


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Image should be geo referenced

Each layer depicts earth a specialcharacteristics of such as topography, soil type

hydrology, vegetation cover.

Rater layer are used to represent continuousspatial phenomena such as elevation,

temperature, pollution concentration.


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Resolution

Dimension represented by each cell. The

minimum linear dimension of the each cells,

expressed in dots per inch on an image or as

actual ground measurement is known as spatial

resolution


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Bits & Image Depth

The amount of computer memory spaced

expressed in terms of bits, that is used to stored

the value of a raster cell is called image depth.

Minimum image depth is one bit

One bit= one and zero


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Black and white scan map one & Zero value

Grey scale map and Aerial photograph

contains- Eight bit

256 bit level of grey image. This image know

as pseudo color image. With red, blue and

green, primary colors. This may be combine indifferent proportion to found different color


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File format of Raster Data

Generic raster file formats

Raster data interchange format

Raster data compression format Remote sensing format

Proprietary format of GIS S/W products


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Generic Raster file format

ASCII file format

Binary file format

These are device independent. It means theyare usable by different application regardless

of hardware and software problems


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Raster data Interchange format

Tagged image file format (TIFF)- Non

proprietary and independent. This format is

widely used by all the organization,

cartographers, commercial purposes, research

purposes.

When tiff is geo referenced known as Geo

reference tiff


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Raster data compression format

It is very essential feature because digital

image file are normally huge and require

immense physical storage resources. The

objective of data compression is to store large

data file to small space. For this GIFF, JPEG are

common format


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Proprietary raster Geospatial data

format

Raster data format are system specific format

of GIS S/W such as

ESRI-Arc GIS

Intergraph/ Erdas-.Img. Grass


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Raster Geo processing and Digital

Image processing

Modal for specific problem

Decision making

Problem solving


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Advantages & Limitations of Raster

Geo processing

Effective representation of continuous surface.

The raster data model represents spatial

phenomena such as topography, land use land

cover and air quality

Fast computer processing:- The process of

overlaying different layer of spatial data is

raster format is simple and less complex.


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Fast display of surface data

Ability to handle large database


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Application which are more easy on

Raster format

Flow of water

Spread of wild fire

Dispersion of pollutant Growth of Settlement


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Application which are more easy on

Vector format

Parcel

Land

Line Street

Coast line


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Acquisition of Raster Geospatial Data

GIS user used to create their own data.


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Us country USGS produce and maintain three

important raster all layer of all over the country

Digital Orthoquadrangle (DOQ)

Aerial photograph is which image

displacement caused by camera tilt and terrain

relief has been removed


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Digital Raster Graphics

Scanned image

1:24000

1:20,000

1:1000000

1:250,000


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Digital elevation model


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Geo reference Raster Data

Image to map rectification

1 Spatial interpolation by co-ordiante

transformation

2- Attribute Interpolation by sampling

Nearest neighbors

Bilinear Interpolation

Cubic Convolution resampling


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Image to Image Registration


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Pre Processing & Editing Raster Data

Image rectification & restoration

Raster data editing


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Image rectification

Image rectification and restoration are the

process that correct the distortion and error,

which comes during data acquisition.

The process are normally applied before the

data are actually used in any applications.

They are commonly called image processing


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Geometric correction

Radiometric correction


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Raster Data editing

Filing holes and Gaps

Edge smoothing or boundary simplification

FilteringErase delete

Thining

ClippingDrawing


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Mosaicking Raster Image

It is a composite picture that is made by

piecing together two are more aerial

photographs or scanned image or satellite

photographs or scanned image or satelliteimage . Many soft were have a ficility to

provide mosaic


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Mosaic

Three categories

Controlled mosaic

Semi controlled mosaic Uncontrolled mosaic


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Raster data were processed separately and usedfor different purposes

Raster Data-Spatio temporal modeling in

environmental application

Vector Data- Digital mapping and resources

inventories


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After Mosaicking

Histogram Matching

Feathering

The purposes of feathering is to blend or blur

the scene between mosaicking images. This is

achieved by changing the grey scale value of the

cell according to the weighted average of their

distance from the edge of the image


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Raster Geospatial Data analysis

Logical operation

Arithmetic operation

Overlay operation

Geometric operation

102 l4 geoinfo raster geoprocessing 03mar13.pptx

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