Automate Your GIS Application: Initiate | Innovate | Automate

4 Jul 2009

by M Rajesh

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GIS

Geostatistical analysis

• What is the geostatistical analysis?
• Explore data (why? methods: histogram, voronoi map, normal QQplot, general QQPlot, trend analysis, semivariogram/covariance cloud, crosscovariance cloud)
• Methods of interpolation (global and local, deterministic and geostatisctical, exact and inexact, nodirectional and ansotropy)
1. IDW (characteristics)
2. Global polynomial
3. Local polynomial
4. Radial Basis Functions (or spline)
5. Kridging (assumption, assessment of prediction errors)
 Ordinary, universal, simple, indicator, cokridging
• Output maps (prediction map, standard error map, quintile map, probability map)
• Cross-validation and validation
• Basic rules for good predictions
1. mean error,
2. RMS prediction error, average standard error, mean standardized error
3. RMS standardized error
4. average standard error vs RMS prediction error (=, >, <)
5. RMS standardized error (=1, <1, >1)

4 Jul 2009

by M Rajesh

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GIS

Spatial analysis

Vector analysis
• Two sets of vector analysis tools in ArcToolBox
o For shapefile, feature class, table
o For coverage
• Extract (clip, select, split), Overlay (erase, identify, intersect, union, update), Proximity (buffer, near, point distance, thiessen polygon)

Raster analysis

• Spatial Analyst Tools (includes groundwater and hydrology tools) and Spatial Analyst extension
• Mapping distance (straight line, allocation function, cost weighted distance, shortest path), mapping density, surface analysis, statistics (cell, neighborhood, zonal), reclassification, raster calculator, vector and raster conversion, hydrology and watershed

Spatial statistics

• Spatial Statistics Tool for vector data and to help asses patterns, trends, and relationships
• Measuring geographic distribution (where is the center), analyzing patterns (random, clustered, or dispersed? Global calculations), mapping clusters (local calculations, hot spot).

4 Jul 2009

by M Rajesh

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GIS

Basic GIS Topics – Review of basic GIS

• What is GIS?
• 3 components (computer system, spatially referenced data, people)
• Spatially reference data or geographic data (geospatial data, attribute data, metadata)
• Geospatial data:
o Characteristics of spatial data (mappable, discrete or continuous, spatial relationships)
o GIS is a simplified view of the real world (discrete or continuous), problems still exist (dynamic and static, identification of discrete or continuous features, scale, fuzzy)
o Topology (adjacency, containment or coincidence, connectivity) and how it works
o Raster, vector, and geodatabase data models
o GIS data or file formats (vector: shapefiles, coverages, TIN; raster: grid and image; Geodatabase (object-oriented data model): vector — feature class, feature datasets, nonspatial table, topology, relationship classes, geometric networks), raster — raster datasets, raster catalogs)
• Attribute data:
o row, column, relational database,
o one-one, many-one, one-many, many-many; join and relate
• Metadata
• Geodatabase (personal and multi-user)

11 Jun 2009

by M Rajesh

1 Comment »

GIS

What is GIS?

GIS allows us to view, understand, question, interpret, and visualize data in many ways that reveal relationships, patterns, and trends in the form of maps, globes, reports, and charts.

A GIS helps you answer questions and solve problems by looking at your data in a way that is quickly understood and easily shared.

GIS technology can be integrated into any enterprise information system framework.

22 Mar 2009

by M Rajesh

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GIS

WebDesign – JavaScript – Adding PDF Icon to Links

First Place an icon file in images folder, then put the following code in <head> tag

<script src=”http://jqueryjs.googlecode.com/files/jquery-1.3.2.min.js”></script>

<script type=”text/javascript”>

$(document).ready(function() {

$(’a[href^=mailto:]‘).addClass(’mailto’);

$(’a[href$=.pdf]‘).addClass(’pdflink’);

$(’a[href^=http][href*=henry]‘).addClass(’henrylink’);

});

</script>

<style>

.mailto {

background: url(images/mail.png) no-repeat right top;

padding-right: 18px;

}

.pdflink {

background: url(images/pdf_button.png) no-repeat right top;

padding-right: 18px;

}

</style>

6 Mar 2009

by M Rajesh

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GIS

RFID

Introduction

RFID (Radio Rrequency IDentification) is a technology that incorporates the use of electromagnetic or electrostatic coupling in the radio frequency (RF) portion of the electromagnetic spectrum to uniquely identify an object, animal, or person. RFID is coming into increasing use in industry as an alternative to the bar code. The advantage of RFID is that it does not require direct contact or line-of-sight scanning. An RFID system consists of three components: an antenna and transceiver (often combined into one reader) and a transponder (the tag). The antenna uses radio frequency waves to transmit a signal that activates the transponder. When activated, the tag transmits data back to the antenna. The data is used to notify a programmable logic controller that an action should occur. The action could be as simple as raising an access gate or as complicated as interfacing with a database to carry out a monetary transaction. Low-frequency RFID systems (30 KHz to 500 KHz) have short transmission ranges (generally less than six feet). High-frequency RFID systems (850 MHz to 950 MHz and 2.4 GHz to 2.5 GHz) offer longer transmission ranges (more than 90 feet).

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4 Feb 2009

by M Rajesh

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GIS

Models for storing and representing spatial data in a GIS system

There are two main models for storing and representing spatial data in a Geographic Information System (GIS): the raster the vector models:

Raster Data – raster (or grid cell type) data can be used for analyzing, overlaying, and modelling area features such as soil types or forested areas. Raster data are generally typically scanned in from maps.
Vector Data – vector data can be used to represent linear features such as roads, streams or area edges and can be combined with raster data for display purposes or for analysis.
In general, Raster maps are faster, Vector maps are more specific and more accurate.

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4 Jan 2009

by M Rajesh

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GIS

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Database Management Systems: Review in the context of GIS Applications

In this section we will examine Oracle database, how this product can be suitable for our GIS projects.
Oracle products are extraordinarily careful with data: For safety, they write all changes to data in two separate places—first to a transaction log and then to the database data file. Support transactions, which guarantees that if a mistake or an error happens as part of a series of related database commands, every related change will be undone in reverse order (an action called a rollback) to preserve database integrity.
Extensive SQL support, transaction support, and scalability are three key features that distinguish Oracle from other products which are adequate for desktop work, such as Microsoft Access.
Elements that are important when you’re choosing database server software for mission-critical projects are…..
Support for security, backup management, replication, programmability, extensibility, fault tolerance, and manageability.
A commitment to open-source standards like Java and XML is another trend. Oracle has all added extensive Java features to its databases…
 
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