1 / 7

GIS Analytical Functionality: Measurement, Connectivity, and Spatial Search

Explore measurement operations such as distance, length, perimeter, and area, as well as connectivity measures and spatial search operations in GIS.

sandovald
Download Presentation

GIS Analytical Functionality: Measurement, Connectivity, and Spatial Search

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lecture 18: GIS Analytical Functionality (II) Topics 2. Measurement 3. Connectivity Readings on the topics Chapter 14 in Longley et al. (2005): pp. 323-330 Other readings Measurement: Chapter 6 Chrisman (2002): pp. 153-168 Connectivity: Chapter 7 in Aronoff (1993): pp. 220-235

  2. Outlines 2. Measurement Operations: 2.1 Distance between features: 2.1.1 Under Raster The spread function (Spread Function Figure) 2.1.2 Under Vector 1) Point to point Straight line: Along a path: ∑di

  3. 2.1.2 Under Vector (continued…) 2) Point to Line To straight line: (Point to Straight Line) To polyline: (Point to Polyline) 3) Point to Polygon (Point to Polygon) 4) Line to Line (Line to Line) 5) Line to Polygon (Line to line) 6) Polygon to Polygon (Line to line)

  4. 2. Measurement Operations: (continued …) 2.2 Lengths of linear features 2.2.1 Under Raster Counting pixels 2.2.2 Under Vector Sum of the lengths of line segments defining the linear feature 2.3 Perimeters of area features 2.3.1 Under Raster Counting the number of exposed edges of exterior pixels (Figure) 2.3.2 Under Vector Sum of the lengths of line segments defining the boundary 2.4 Area of area features 2.4.1 Under Raster Counting the number of pixels of the same label 2.4.2 Under Vector The trapezoid approach (The Trapezoid approach)

  5. 3. Connectivity Operations: 3.1 Connectivity measures 3.1.1 Under Raster 4-connected (Diagram) 8-connected (Diagram) 3.1.2 Under Vector Objects are identified under vector data model. connectivity can be determined based on physical connection 3.2 Proximity (buffering) 3.2.1 Under Raster Calculating distance and thresholding (Raster Buffering) The Nature of error with buffering under raster (Error) 3.2.2 Under Vector Construct buffers for individual line segments and then resolve the overlaps (Vector Buffering)

  6. 3. Connectivity Operations (Continued…) 3.3 Intervisibility operation (viewshed analysis) (Raster only, requires a DEM) Find out the area which can be seen from a point (viewshed) 3.4 Spatial Search The Point-In-Polygon Operation (Point-In-Polygon)

  7. Questions: 1. How to determine the size of a particular patch under the raster data model? (the size of one patch) 2. Buffering under raster is not accurate. Why people say that? What is a commission error and a omission error under the context of a raster buffer? 3. What is 4-connected and what is 8 connected? 4. How would one determine if a point is in a particular polygon or not? Why do people say that point-in-polygon is the fundamental operation for spatial search?

More Related