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

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

Full Name *
Reg# *
Class# *
Section *
Email *

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

Contour Map from DEM file

Prerequisite Software: ArcGIS 9.3

  1. Download the required DEM file from DEM Datasources. One of the datasource for DEM files is databasin. For following example, I downloaded Asia DEM file.
  2. Extract Portion of DEM Geoprocessing in ArcMap.
    1. Open new empty map in ArcMap.
    2. Drag and drop your DEM file from ArcCatalog to ArcMap. In my case, the dem file is 000asia_dem.
    3. Open ArcToolbox from icon on Standard Toolbar in ArcMap or from Windows>ArcToolbox.
    4. In ArcToolbox, click Spatial Analysis Tool > Extraction > Extract by Rectangle. In my case, I have entered following coordinates:
      • left = 70.59
      • right = 73.064
      • top = 34.849
      • bottom = 32.525
    5. Select aisa_dem in inputraster dropdown box.
    6. Browse to your given folder in output raster box and press ok. Also enter the name of the file to save. In my case it is surveydata.
    7. Extracted DEM will be created as new layer.

  3. Create Contour from DEM file.
    1. Open new empty map in ArcMap.
    2. Drag and drop the extracted DEM file from ArcCatalog to ArcMap. If it ask to create pyramids for dem file, press yes.
    3. Open Spatial Analyst Toolbox from right click on empty space of Standard Toolbar or goto view > Toolbars>Spatial Analyst.
    4. Goto Spatial Analyst > Surface Analysis > Contour
    5. Select in input box the given DEM layer.
    6. Set the Contour Intervals or keep the default values.
    7. Select the Output folder for Feature and give name to the shape file. In my case the name is surveycontour.shp. Press ok.
    8. A contour file will be created as new layer.

You can check the dem2contour poster for demo.