Topology Rules Explained

To clarify a previous post where the project's topology rules are stated, the following is an explanation of each given topology rule in detail.

Must contain point

A polygon in one feature class must contain a point from another feature class. The point must be within the polygon, not on the boundary. Used to ensure each lease polygon contains a resource extraction point.

Endpoint must be covered by

The endpoint of a line must be covered by a point from another feature class. Used to ensure each pipeline ends in a resource extraction point.

Must be properly inside

Requires that all the points of one feature class fall within the polygons of another feature class. Used to ensure that each resource extraction point falls within a polygon.

Must not overlap

A line feature cannot overlap another line of the same feature class. Used to ensure that creeks and roads never share segments but can still intersect.

Must not self overlap

Ensures that a line feature cannot overlap itself. This will be used with roads that end in a loop, ensuring the loop doesn't overlap the remainder of the road.

Must be covered by

Points from one feature class must be covered by a line in another feature class. This will be used to ensure that all crossings are located along a segment of a road.

Must not overlap with

The interior of one polygon cannot overlap with that of another polygon in a different feature class. This will be used to ensure that boundary polygons do not overlap lakes.

Must not overlap

The interior of one polygon cannot intersect another polygon of the same feature class. This will be sued to ensure that reserves do not overlap.

Must not have gaps

This rule ensures that there no voids or gaps within a polygon or beside adjacent polygons of the same feature class. This will be used to ensure that site prep polygons all fit tightly togther within a harvest black boundary without any gaps.

Must cover each other

Requires that the polygons of one feature class must share all of their area with the polygons of another feature class. This will be used to ensure that the site prep polygons fit exactly on top of the harvested blocks polygon.

Topology Rules for Project Design

In order to showcase the many uses of topology, a wide variety of topological rules will have to be applied to this database. The following is an outline of of the feature datasets that will be used and the rules that will be applied to them. Feature classes are in regular print while topological rules are in bold.

Resource Extraction Dataset

• Lease sites must contain Resource Extraction point
• Pipelines endpoint must be covered by Resource Extraction point
• Resource extraction point must be properly inside of Lease site

Block Creeks Dataset

• Creeks must not overlap

Block Road Dataset

• Roads must not overlap
• Roads must not self overlap
• Crossings must be covered by Roads

Block Boundary Dataset

• Block boundary must not overlap with Lakes and rivers
• Reserves must contain point Wildlife points
• Reserves must not overlap

Site Preparation Dataset

• Type of site prep. must not have gaps
• Harvested blocks must cover Type of site prep.

For clarification of further blogs the heiarchy of data will be explained below with 1 being the largest file and highest level.

1. File Geodatabase
2. Feature Dataset
3. Feature Class

You must be working within a geodatabase in order to apply topology rules to feature classes within a feature dataset.

Project Design

Topology is of a special importance to forestry data entry due to the large amount of GPS data collected. This project will be based around simulated GPS data collection being overlayed onto a base dataset, which will be topology and geographically correct.

Project Title: Using topology to simulate problems that can arise during data entry in forestry situations when several uncorrected feature datasets are overlayed on a topologically correct dataset.

the base dataset, which will be taken from CANFOR Grande Prairie divisions FMA, will include the following topologically correct layers:

1. Routed roads
2. Lakes and rivers
3. AVI vegetation inventory
4. Harvested blocks
5. Pinelines
6. Lease sites
7. Net loss

The simulated forestry operations which will have collected GPS data that will be overlayed onto the base data will each be in their own data set. This will allow topology rules to be set which will correct each data set while allowing interaction between data sets ie. Resource extraction points must fall within lease sites.

GPS block layout data

1. Block boundary (poly)
2. Block roads (line)
3. Crossings (point)
4. Block creeks (line)
5. Wildlife points (point)
6. Resource extraction points (point)
7. Reserves (poly)

Site preparation

1. Type of site prep. within block (poly)
2. Site prep. lines (line)
3. Fuel Caches (point)
4. Points of interest (point)

Beetle probing

1. Plot center (point)
2. Transect lines (line)
3. Plot outline (poly)
4. Beetle locations (point)