Category: GIS related


VRI data analysis

1. The biggest polygon is 14755.71 ha
2. The smallest polygon is 0.000000001216 ha which is a sliver
3.The most predominant species is lodge pole pine
4.The sum of the area of polygons containing some birch is 159591.251
5. DBH stands for diameter at breast height
6.2512687.719
7.a2084408.2849
b878592.286
c4390881.675
8.1953-2007

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1.is an angular measurement in a spherical coordinate system. The vector from an observer to a point of interest is projected perpendicularly onto a reference plane; the angle between the projected vector and the reference vector on the reference plane is called the azimuth.

2.Euclid was a greek mathemetician, Also called the father of geometry ,Euclidian distance is the ordinary distance between two points.

3.Pythagorean theorem is a mathematics related to Eucludian geometry among the three sides of a right triangle, In any right triangle, the area of the square whose side is the hypotenuse (the side opposite the right angle) is equal to the sum of the areas of the squares whose sides are the two sides that meet at a right angle. The equation is a2xb2=c2 which is often called the pythagorena equation.

4.Map algebra is a simple and an elegant set based algebra for manipulating geographic data, in arc gis map algebra is used to preform operations using objects,actions and qualifiers.

5.The 7 key functions of a spatial analysist consist of,

Derive new information from existing data
Apply Spatial Analyst tools to create useful information—for example, derive distance from points, polylines, or polygons; calculate population density from measured quantities at certain points; reclassify existing data into suitability classes; or create slope, aspect, or hillshade outputs from elevation data.

Find suitable locations
Find areas that are the most suitable for particular objectives (for example, siting a new building, or analyzing high risk areas for flooding or landslides) by combining layers of information. Based on a set of input criteria (for example, where areas of vacant land with the least steep terrain that are nearest to roads would be most suitable), areas in green in the graphic below are the most suitable locations for building; areas in red are least suitable. Areas in yellow are of medium suitability.

Identify the best path between locations
Identify the best path or optimum corridors for roads, pipelines or animal migration. Factor in economic, environmental, and other criteria.

Perform distance and cost-of-travel analyses
Create Euclidean distance surfaces to understand the straight-line distance from one location to another, or create cost-weighted distance surfaces to understand the cost of getting from one location to another based on a set of input criteria you specify

Perform statistical analysis based on the local environment, small neighborhoods, or predetermined zones
Perform calculations on a per-cell basis between multiple rasters, such as calculating the mean crop yield over a 10-year period. Study the neighborhood by calculating, for example, the variety of species in a neighborhood. Determine the mean value in each zone, such as the mean elevation per forest zone.

Interpolate data values for a study area based on samples
Measure phenomenon at strategically dispersed sample locations, and predict values for all other locations by interpolating data values. For instance, create raster surfaces from elevation, pollution or noise sample points.

Clean up a variety of data for further analysis or display
Clean up raster datasets that contain data that is erroneous or irrelevant to the analysis at hand or is more detailed than you need.

libya update

http://www.cnn.com/2011/WORLD/africa/03/04/libya.conflict/index.html?hpt=T1#

my buffers

moosefire
The road is buffere in intervals of 5m to see which trees should be removed in order to remove trees to stop a forest fire from jumping and then there is prime moose habitat with 50 m buffer rings in order to make sure the road does not come to close to the road in order to prevent wildlife collisions

point-to see the blast zone of an explosive, where the bomb is detinated and then what surrounding area is effected.

line/road-to see what areas of the forest need to be cut around the road in order to stop forest fire from jumping the road

point-where the hardest hit area of an earthquake is, the earth quake buffer itself and then a buffer on the effected area to send in medical help

line-a buffer on a proposed road to see how close moose habitat is in order to prevent animal collisions

point-using a buffer on a building site of a house to see if it will have any noise polution/crime/air quality issues(of course living in pg most area have air quality issues HA)

http://news.sympatico.ctv.ca/home/stock_market_players_fuel_gas_hike_experts_say/a7974128

1. TIN-(Triangulated Irregular Network) A vector-based data structure for storing terrain information in digital terrain modeling, it is a surface representation derived from irregularly spaced points and breakline features. Each sample point has an x, y coordinate and a z value or surface value.

2. Interpolated values-interpolation is a method of constructing new data points within the range of a discrete set of known data points, the interpolated values can be represented by color or number etc.
3. Mass points-An irregularly distributed sample point, with an x-, y-, and z-value, used to build a triangulated irregular network(TIN). Ideally, mass points are chosen to capture the more important variations in the shape of the surface being modeled.


4. DEM-(data elevation model)-a DEM file is a simple, regularly spaced grid of elevation points .A DEM can be represented as a raster (a grid of squares, also known as a heightmap when representing elevation) or as a triangular irregular network (TIN). The TIN DEM dataset is also referred as a primary (measured) DEM, whereas the Raster DEM is referred as a secondary (computed) DEM


5. Contiguous data-Data that are stored in a collection of adjacent locations in a computer memory device,
contiguous data is data that is moved or stored in a solid uninterrupted block. In general, contiguous data can be accessed more quickly than data that is stored in fragments because fewer access operations will be required. Files are sometimes stored in fragments so that storage space can be used more efficiently (all the small spaces can be used).

6. Re-sampling-can refer to re sizing of images or data sources it can also be a filter to the data and changes the sampling rate of the signal by decimation or interpolation.

7. Raster- Raster data is a grid of cells covering an area of interest. Each pixel, the smallest unit of information in the grid, displays a unique attribute.An example of raster data is a scanned image or photograph. A line drawn in a raster format must be defined by a group of pixels along the length of the line. As a result the size of a raster file is larger than that required by a vector file.

8. Cell-is a three-dimensional polyhedron element that is part of the boundary of a higher-dimensional polytope

9. Zone-a zone is an area of set perametres that has information inside of the certain area
for example pg is in utm zone 10, a specific area that has been divided out of the bc zones.

10. Grid-can be used to define locations on maps using Cartesian coordinates. Grid lines on maps define the coordinate system, and are numbered to provide a unique reference to features.
for example x,3 y,7

information from:
gislounge.com/triangulated-irregular-network-tin/
en.mimi.hu › GIS
www.wikipedia.org/

http://www.vterrain.org/Elevation/dem.html
http://www.answers.com/topic/contiguous-data
http://www.mathworks.com/help/toolbox/ident/ug/bqvevmu-1.html
http://www.cadresources.com.au/
http://www.google.ca/images?um=1&hl=en&rls=com.microsoft:en-us&q=utm%20zone&ie=UTF-8&source=og&sa=N&tab=wi
http://www.google.ca/
http://www.gis.com/

File types

.DWG(drawing)- a file type used for storing two and three dimensional formats, it is used in such programs as INTELLICAD and AUTOCAD

.DXF(Digital exchange format)-File type used as an exact representation of the data in the AutoCAD native file format, the .dxf file has become less useful since AutoCAD has become more powerful.

.DWF(digital web format)-dwf is a secure file format developed byAutodesk for the efficient distribution and communication of rich design data to anyone who needs to view, review, or print design files.

.DGN(Design) This is the file type for CAD file formats which can be supported by microstation, the dgn format has two versions.

.CSV(comma seperarted values)-A file format which is used to store tabular data

.TXT(text)-A file format that is structured for a series of lines containing characters.

.XML(extensible markup lanugage)- a set of rules in machine readable forms which is encoded into documents

.GML(Geography markup language)-is the XML grammar defined by the open geospatial consortium to express geographical features.

.KML(keyhole markup language)- is an XML schema for expressing geographic annotation and visualization within internet based, two-dimensional maps and three-dimensional earth browsers.

.KMZ(Keyhole markup-zipped) A kmz file is a zipped keyhole markup language used to decrease the size of data.

Info source-http://www.wikipedia.org/

Summary review questions

1. Generalization is neccesary because people can not process so many details at one time, if you have tiny tiny details on a map alot of it wont mean anything.

2.The larger the scale the more detailed the map can be but when a map is at a small scale then things have to be generalized in ways such as using points instead of a city polygon

3.As the scale decreases the features become less detailed and more of a generalization

4.simplifacation determines the most important characters and selection makes it have fewer features and details.

5.The three types of data categorisation are nominal,ordinal and interval

Quantum GIS

          Quantum GIS is a user friendly GIS software, it runs on Linux, Unix, Mac OSX, and Windows and supports numerous vector, raster, and database formats and functionalities.QGIS has alot of features similar to ARC such as identify/select features,feature labeling, scale bar/north arrow etc. Also in QGIS you can view and overlay vector and raster data in different formats and projections without conversion to an internal or common format. This software was developed by Gary Sherman began in early 2002, For Mac users, the advantage of Quantum GIS over Grass GIS becauseit does not require the X11 windowing system in order to run, and all around the interface is much cleaner and faster. QGIS offers a selection of plug- ins to better increase the preformance of the free QGIS software, in reviews the QGIS user is satisfied with the product except for the lack of some tools but for a free program it is surprisingly versartile and has some good tools as well for example the editing tools make it simple and easy to create and edit projects.Quantum GIS is available free on their website.

http://www.qgis.org/