GEOG 3830 Geographic Information Systems

Transcription

1 1 GEOG 3830 Geographic Information Systems Lab 08: Spatial Relationships The objective of this lab exercise is to introduce students to a technique commonly used to evaluate the most basic types of spatial relationships: Proximity: distance between features > 0 Adjacency: distance between features = 0 Intersection: overlapping features Containment: features completely within other features The technique employed in this exercise consists of two steps. Step 1: Select a map to be analyzed (Map 1). This step may also include selecting a specific feature in the map to be used in the analysis. Step 2: Select features in the active theme (Map 1) based on their spatial relationship to a feature in another map (Map 2), or to the previously selected feature in the same map (Map 1). Data used in this exercise: Points o Cities (ESRI Sample Data) Polygons o Counties (ESRI Sample Data) o Quad Maps (ESRI Sample Data: USA CD) o Watersheds (USGS: National Atlas Web Site) Lab Instructions Students are advised to review ALL instructions before starting the lab exercise. Lab Report After completing Step 1 of the lab exercise (create lab folder), download, unzip and review the lab report.

2 2 1. Create Lab Folder In Windows Explorer, navigate to C:\3830 Create lab folder File - New - Folder o Folder name = Setup ArcView Project In ArcView, make a New View (View 1) Views - New Specify which folder to use when saving and retrieving data File Set Working Directory o C:\3830\08 Load Extensions File - Extensions o Geoprocessing Save the project to the lab folder File - As o File name = lab08.apr

3 3 3. Download and Unzip Data This section describes the steps to navigate to the USGS National Atlas web site and to locate and download watershed boundary maps (Hydrologic Units). In Internet Explorer, Navigate to the USGS National Atlas Select the following links Atlas Maps Map Layers Data Warehouse Locate Watershed Maps Hydrologic Unit Boundaries Shapefile: hucs00m020.tar.gz Download file to lab folder Save this file to disk UNZIP file in lab folder NOTE: the unzipped file (hucs00m020.tar) also has to be unzipped 4. Proximity Analysis I This section describes how to identify cities that are within 50 miles of Auburn, AL. Display Counties Map View - Add Theme o In Folder: C:\esri\esridata\usa o Counties Turn ON display of Counties Zoom In to Alabama

4 4 Display Cities Map View - Add Theme o In Folder: c:\esri\esridata\usa o Cities Turn ON display of Cities Select Auburn Active Theme = Cities Use Identify Tool to locate Auburn Use Select Tool to select Auburn Select cities within 50 miles of Auburn o Select features of active theme that: o The selected features of: o Selection distance: o New Set Are within distance of Cities 50 miles Table - Promote City Name State Name Clear Selected Features Edit Select None File Close File - Save

5 5 5. Adjacency Analysis This section describes how to identify counties that are adjacent to Lee County, AL. Select Lee County Active Theme = Counties Use Select Tool to select Lee County Select counties adjacent to Lee County o Select features of active theme that: o The selected features of: o Selection distance: o New Set Are within distance of Counties 0 miles Table - Promote County Name State Name Clear Selected Features Edit Select None File - Close File - Save

6 6 6. Proximity Analysis II This section describes how to identify the number of counties that are within 50 miles of Lee County, AL, and their population in 1990 and Select Lee County Active Theme = Counties Use Select Tool to select Lee County Select counties within 50 miles Lee County o Select features of active theme that: o The selected features of: o Selection distance: o New Set Are within distance of Counties 50 miles Table - Promote NOTE: Number of records selected is displayed in upper left corner of window Summarize Results by State Active Field = State Name (click left mouse button on column label) Field - Summarize o Field: Pop 1990 o Summarize by: Sum o ADD o Field: Pop 1999 o Summarize by: Sum o ADD o OK NOTE: Count = Number of Counties Close Summary Table File - Close

7 7 Clear Selected Features Edit Select None File - Close File - Save 7. Intersection Analysis I This section describes how to identify the number of major watersheds (hydrologic units) that overlap the state boundaries of Alabama. Select Alabama Counties Active Theme = Counties Theme - Query o State name = Alabama o New Set o Close Query Window View Zoom to Selected Convert selected features to a new map (Alabama Counties) Active Theme = Counties Theme - Convert to Shapefile o Filename: al_counties Add shapefile to view? YES Turn ON display of Al_counties Turn OFF display of Counties and Cities Delete Counties.shp and Cities.shp Edit - Delete Theme

8 8 Display Watersheds Map View - Add Theme o hucs00p020 Turn ON display of Watershed Map (hucs00p020) Select watersheds that intersect Alabama Active Theme = hucs00p020 Select features of active theme that: Intersect The selected features of: Al_counties New Set Convert selected features to a new map (Alabama Watersheds) Active Theme = hucs00p020 Theme - Convert to Shapefile o Filename: al_hucs Add shapefile to view? YES Turn ON display of Al_hucs Turn OFF display of hucs00p020 Delete Hucs00p020.shp Edit - Delete Theme Active Theme = al_hucs NOTE: Total number of watersheds displayed in upper left corner of window File - Close File Save

9 9 8. Containment Analysis This section describes how to identify the number of major watersheds (hydrologic units) that are completely within the state boundaries of Alabama. Turn OFF display of Al_hucs Create Alabama State Boundary Map Active Theme = al_counties View - Geoprocessing Wizard o Dissolve features based on attribute NEXT o Theme to dissolve: al_counties o Attribute to dissolve: state_name o Output file: al_state NEXT o Choose additional field to include: State FIPS by First o This part is required, but it s not important in this exercise. FINISH Turn ON display of Al_state Change display color to transparent Turn ON display of Al_hucs Select watersheds completely within Alabama Active Theme = al_hucs Select features of active theme that: Are completely within The selected features of: al_state New Set Active Theme: Huc_al NOTE: Number of selected watersheds displayed in upper left corner of window

10 10 Clear Selected Features Edit Select None File Close File Save 9. Intersection Analysis II This section describes how to identify the number of USGS 7.5 Quad Maps that overlap the state boundaries of Alabama. Display USGS Quads Map View - Add Theme o In Folder C:\usa_2mg\quad_24ks o Polygon o NOTE: In the Legend Window, the file will be displayed as Q_24ks Turn ON display of Quads Map (Q_24ks) Select quads that intersect Alabama Active Theme = Q_24ks Select features of active theme that: Intersect The selected features of: Al_state New Set Convert selected features to a new map (Alabama Quad Maps) Active Theme = Q_24ks Theme - Convert to Shapefile o Filename: al_quads Add shapefile to view? YES Turn ON display of Al_quads

11 11 Turn OFF display of Q_24ks Delete Q_24ks Edit - Delete Theme Drag Al_state to Top of Legend Window to view overlap of quads and state boundary Active Theme = al_quads NOTE: Total number of quads displayed in upper left corner of window File - Close File Save