CHAP 07 REVIEW Q&A

Question 1

1. In your own words, briefly explain what modern day “metes and bounds” surveying is.
2. Briefly describes what “lot and block” surveying is. What is the benefit of describing a property with a lot and block survey, instead of with metes and bounds?

Answer 1

1. Metes and bounds is a survey method which describes the boundaries of a property using compass bearings and distance measurements. Starting with a physically defined reference point, the surveyor proceeds in a straight line to the next defined point on the boundary of the property (e.g. to a corner of the property), noting the direction travelled (compass bearing) and measuring the distance. The surveyor proceeds from there to the next point on the property’s periphery, again noting the direction and distance travelled. The surveyor proceeds to each successive point until they have returned to the beginning point (thus “bounding” or closing the property). These compass bearings and distances can then be used to objectively define the property’s external dimensions.
2. Lot and block surveying is often used in urban areas to subdivide larger parcels of land into smaller units. Each lot would be surveyed using metes and bounds and this information would be recorded on a map (usually held at the land title office). The legal description of each lot can then be referenced to this map and referred to by number (e.g. Lot 22, Blok 5, Map Block 10, Page 20), instead of requiring the full metes and bounds description. This makes describing property location easier, which is helpful for conveyancing or assessment purposes.

Question 2

How are the problems created by tilt displacement and relief displacement corrected?

Answer 2

Tilt displacement is removed through rectification

Relief displacement is corrected with an orthophotograph which is a composite of thousands of tiny photographs.

Question 3

1. What are the advantages of a geographic information system over other methods of computerized mapping?
2. What are the potential problems of a multi-user system of computerized mapping and how can they be minimized?

Answer 3

Advantages of Geographic Information System

• integrates spatial and attribute data; e.g. location and soil type or number of bathrooms.
• can combine map layers depending on specific information needs.
• can access specific information about each property or group of properties
• applicable to many different users as assessors, planners, engineers, resource specialists, surveyors, the land registry office.
• can be used by assessors to model the impact of location on value.

Problems and potential solutions in a multi-user system.

Problem ; user without specialized knowledge in a particular area updating system.

Potential Solution : restrict user access to system. e.g. read only privileges instead of read and write privileges to ensure information can only be altered by those with special knowledge.

Problem : information not kept up-to-date by user with special information

Potential Solution : audits by a centralized agency; staff each user department with a specialist from a centralized agency who reports to the centralized agency and provides advice to the user department; remove privileges for violations.

Question 4

In setting up a GIS in an assessment office, why is cleansing the parcel data important?

Answer 4

Essentially, this is based on the old computer expression “Garbage in, Garbage out”, If you want good analysis, it must be based on good data.