QGIS Lab10 Fall14: QGIS Raster Analysis

Introduction:

This is tenth video tutorial of QGIS. It is about raster analysis. The objective is to learn and use raster analysis in qgis.

Summary:

  1. Load analysis.qgs
  2. Set project crs to 33S
  3. Add four settelite files and create virtual raster catalog. Raster > Miscellaneous > Build Virtual Raster (Catalog).
  4. Save in exercise_data/residential_development as aerial_photos.vrt
  5. Raster > Projections > Warp (Reproject). to 70300
  6. Raster > Miscellaneous > Merge.
  7. Changing Raster Layer Symbology and using View > Toolbars > Raster
  8. Terrain Analysis (hillshade, Slope and Aspect)
  9. Using the Raster Calculator, aspect@1 <= 90 OR aspect@1 >= 270, save it in aspect_north.tif and also calculate slope_lte2.tif and slope_lte5.tif.
  10. Write criteria for location: ( aspect_north@1 = 1 AND slope_lte5@1 = 1 ) OR slope_lte2@1 = 1 and save it as all_conditions.tif.
  11. Simplifying Raster: all_conditions_sieve.tif and Threshold and Pixel connections values to 8
  12. Open the Raster Calculator again, and build this expression: (all_conditions_sieve@1 <= 0) = 0 and save output as: all_conditions_simple.tif
  13. Raster > Conversion > Polygonize (Raster to Vector). Field name = suitable and save it as: all_terrain.shp
  14. For filer of suitable = 1, save it as suitable_terrain.shp
  15. Raster > Conversion > Rasterize (Vector to Raster) for suitable_terrain.shp, width = 837 and height = 661
  16. Use the Intersect tool (Vector -> Geoprocessing Tools) to create a new vector layer called new_solution.shp which contains only those buildings which intersect the suitable_terrain layer.

Below is the full video lecture. Use full screen for clear content of video. The download link of below video is ogg video or mp4 video. You can play it in vlc player or open it in web browser.

The example files that are used in video can be downloaded from here .

Reference:

  1. Chapter 08 of QGIS 2.6 Training Manual

QGIS Lab09 Fall14: QGIS Spatial Statistics

Introduction:

This is ninth video tutorial of QGIS. It is about spatial statistics. The objective is to learn and use statistics tools in qgis and from SAGA modules from processing toolbox.

Summary:

  1. Required Data layer: srtm_41_19.tif and road_34S.shp
  2. Convert Layers to 33S
  3. Vector > Geoprocessing Tools > Convex Hull
  4. Vector > Research Tools > Random points
  5. Save our output in exercise_data/spatial_statistics/ as random_points.shp
  6. Plugins > Analyses > Point sampling tool
  7. Save the output under exercise_data/spatial_statistics/ as random_samples.shp
  8. Vector > Analysis Tools > Basic statistics and use random_samples
  9. Create 03 points random data in distance_points layer and use Vector > Analysis Tools > Distance matrix.
  10. Vector > Analysis Tools > Nearest neighbor analysis and use random_samples.shp
  11. Vector > Analysis Tools > Mean coordinate(s) and use random_samples.shp and save resulting layer as mean_coords.shp
  12. Vector > Geometry Tools > Polygon centroids and save resulting layer as center_point.shp
  13. Using image histogram.
  14. Raster > Analysis > Grid (Interpolation) and saving output to exercise_data/spatial_statistics/interpolation.tif. Power to 5.0 and the Smoothing to 2.0
  15. Processing > Toolbox and use Spatial Point Pattern Analysis (use random_sample layer) and Minimum Distance Analysis (use random points layer)

Below is the full video lecture. Use full screen for clear content of video. The download link of below video is ogg video or mp4 video. You can play it in vlc player or open it in web browser.

The example files that are used in video can be downloaded from here .

Reference:

  1. Chapter 07 of QGIS 2.6 Training Manual

QGIS Lab08 Fall14: QGIS Network Analysis

Introduction:

This is eighth video tutorial of QGIS. It is about network analysis. It contains example problem. The objective is to learn and use road graph plugin.

Summary:

  1. Road Graph Plugin.
  2. Using Road Graph plugin with speed option (Selecting route by shortest time.).
  3. Selecting using polygon and filling only selected fields.Also use selection by query expression.
  4. Split Feature in edit mode.
  5. Topology Tolerance in Road Graph Setting.
  6. Saving our shortest path to new layer.

Below is the full video lecture. Use full screen for clear content of video. The download link of below video is ogg video or mp4 video. You can play it in vlc player or open it in web browser.

The example files that are used in video can be downloaded from here .

Reference:

  1. Chapter 07 of QGIS 2.6 Training Manual

QGIS Lab07 Fall14: QGIS Vector Analysis

Introduction:

This is seventh video tutorial of QGIS. It is about vector analysis. It contains example problem. The objective is to ask a question and solve it using analysis tools.

Summary:

  1. The GIS Process:
    1. State the Problem
    2. Get the Data
    3. Analyze the Problem
    4. Present the Results
  2. The Problem:
    1. It needs to be in Swellendam.
    2. It must be within reasonable driving distance of a school (say 1km).
    3. It must be more than 100m squared in size.
    4. Closer than 50m to a main road.
    5. Closer than 500m to a restaurant.
  3. The data:
    1. The residential properties (buildings) in the area.
    2. The roads in and around the town.
    3. The location of schools and restaurants.
    4. The size of buildings.
  4. Solution:
    1. Vector > Geoprocessing Tools > Buffer
    2. Vector > Geoprocessing Tools > Intersect
    3. Vector > Research Tools > Select by Location
    4. Layer > Query (ctrl + F)
    5. Field Calculator (press ctrl + I in attribute table window)
    6. Creating Data by downloading OSM file (osm_data.osm) of given region. lat: -33.9757, -34.0877 Lon: 20.353, 20.5278
    7. Extraction following data:
    8. Convert crs to 34S
    9. Buffer road to 50m and schools to 1KM
    10. Find overlaping area by intersect and save it as road_school_buffers_intersect.shp
    11. Select houses in that region by location and save it to well_located_houses.shp.
    12. Create buffer to resturant and save it as houses_restaurants_500m.
    13. Repeat step 7.
    14. Select Buildings of the Right Size by creating area column and using query filter (ctrl + F).
    15. Saving result in solution.shp

Below is the full video lecture. Use full screen for clear content of video. The download link of below video is ogg video or mp4 video. You can play it in vlc player or open it in web browser.

The example files that are used in video can be downloaded from here .

Reference:

  1. Chapter 07 of QGIS 2.6 Training Manual

QGIS Lab06 Fall14: QGIS Vector Reprojection

Introduction:

This is sixth video tutorial of QGIS. It is about vector reprojection.

Summary:

  1. Reprojecting and Transforming Data
  2. Projections
  3. “On the Fly” Reprojection (OTF):
    1. What this means is that even if the data itself is in another CRS, QGIS can project it as if it were in a CRS of your choice.
    2. Also using NSIDC EASE-Grid Global  i.e., Projected Coordinate System (PCS) to keep scale constant.
  4. Saving a Dataset to Another CRS
  5. Calculating area using Field Calculator
  6. Creating Your Own Projection
  7. Data Required:
    1. exercise_data/world/world.qgs
    2. exercise_data/world/RSA.shp
    3. exercise_data/epsg4326/buildings.shp
    4. world/oceans.shp

Below is the full video lecture. Use full screen for clear content of video. The download link of below video is ogg video or mp4 video. You can play it in vlc player or open it in web browser.


The example files that are used in video can be downloaded from here .

Reference:

  1. Chapter 07 of QGIS 2.6 Training Manual
  2. Working with Projections (Spatial Thoughts Blog)
  3. Reprojecting Vector Layer (Info Geo Blog)

Quiz03: CE318L GIS/RS for Civil Engineers Fall14

This quiz is on following topics:

    Raster Analysis
    Delimited Text
    Geoprocessing

First Enter your full name, registration#, class#, section and email. You are required to answer all questions. Select only one option. Time limit is 10 minutes. Good luck.

Quiz03: CE318L GIS/RS for Civil Engineers Fall14

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Quiz02: CE318L GIS/RS for Civil Engineers Fall14

This quiz is on following topics:

    Creating Point, Line and Polygon
    Georeferencing
    Digitization
    Geocoding

First Enter your full name, registration#, class#, section and email. You are required to answer all questions. Select only one option. Time limit is 10 minutes. Good luck.

Quiz02: CE318L GIS/RS for Civil Engineers Fall14

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Class# *
Section *
Email *

QGIS Lab05 Fall14: QGIS Practice Session – Displaying flood data using CSV file.

Introduction:

This is fifth video tutorial in urdu language for QGIS. It is overview lecture on practice session using csv to display flood data.

Summary:

  1. Display Flood data using CSV.
  2. Delimited Text, text/csv file, excel spreedsheet.

Below is the full video lecture. Use full screen for clear content of video. The download link of below video is ogg video or mp4 video. You can play it in vlc player or open it in web browser.

The example files that are used in video can be downloaded from here .

Reference:

  1. CSV files in QGIS
  2. How to Create Beautiful Maps in QGIS
  3. Stamen Maps for QGIS

QGIS Lab04 Fall14: QGIS Delimited Text, Contour from Vector Points, Geoprocessing

Introduction:

This is fourth video tutorial in urdu language for QGIS. It is overview lecture on basic tasks such as loading delimited text, working with text/csv file, working with excel spreadsheet and geoprocessing.

Summary:

  1. Delimited Text, text/csv file, excel spreedsheet.
  2. Contour from Point Vector layer
  3. Geoprocessing

Below is the full video lecture. Use full screen for clear content of video. The download link of below video is ogg video or mp4 video. You can play it in vlc player or open it in web browser.
More better explanation for importing polygons using csv files is in below video. It explains use of different delimiter other than comma (,).
The download link of below video is ogg video or mp4 video. You can play it in vlc player or open it in web browser.

 

The example files that are used in video can be downloaded from here .

Reference:

  1. CSV files in QGIS
  2. Contour from Points
  3. Geoprocessing
  4. Slides on Geoprocessing