1. Geospatial Analysis
with Open Source GIS
Chingchai Humhong and Sakda Homhuan
Regional Center of Geo-Informatics and Space Technology, Lower Northern Region
Naresuan University
chingchai.h@gmail.com, chingchaih@nu.ac.th
sakda.homhuan@gmail.com
3. fTools Plugin
The goal of the fTools python plugin is to provide a one-stop resource
for many common vector-based GIS tasks, without the need for
additional software, libraries, or complex workarounds.
fTools is now automatically installed and enabled in new versions of
QGIS, and as with all plugins, it can be disabled and enabled using the
Plugin Manager.
18. [A]
[A, C]
[A, C]
[A, C, D]
[A, C, D, E, F, G, H, I, J]
[A, C, D, E, F, G, H, I, J, K, L, M, N, O]
Select by location
Input feature: green
Input feature's center: red X
Selecting feature: gray
19. [A, B]
[A, C, D, E, F, G, H, I, J, K, L, M, N, O]
[A, C, D, E, F, G, H, I, J, K, M]
Select by location
Input feature: green
Input feature's center: red X
Selecting feature: gray
20. Select by location
The Select By Location lets
you select features based
on their location relative to
other features.
32. Line clipped by polygon:
Point clipped by polygon:
Polygon clipped by polygon: Line clipped by line:
Point clipped by point:
Clip: Input and output
40. The rainfall P (mm) distribution in Sirsa district:
(a) temporal variation,
(b) spatial variation,
(c) meteorological regions using Thiessen polygons.
Voronoi (Thiessen) polygon
46. Projected coordinate systems
(A) Mercator's projection – an equatorial cylindrical
projection – yields a map (B) on which areas become
increasingly distorted toward the poles (each of
which is drawn out into a line at an infinite distance
from the equator.
(C) An azimuthal projection from the north pole
provides a useful map (D) of the southern
hemisphere.
(E) A conic projection, with elements touching the
globe at one (as here) or more parallels, is well
suited to mapping mid-latitude regions (F). Red
circles represent equal areas, showing the type of
distortion produced.
Spatial reference:
57. QGIS Raster Tools [GDAL]
What is GDALTools?
The GDAL Tools plugin offers a GUI to the collection of tools in the
Geospatial Data Abstraction Library, http://gdal.osgeo.org . These are
raster management tools to query, re-project, warp, merge a wide
variety of raster formats. Also included are tools to create a contour
(vector) layer, or a shaded relief from a raster DEM, and to make a
vrt (Virtual Raster Tile in XML format) from a collection of one or
more raster files. These tools are available when the plugin is installed
and activated.