Data can isolines be generated from

Data can isolines be generated from

Isarithmic mapping

·         2D representation of a 3D surface, using quantitative line symbols (lines of constant value called isolines/isarithms). Such as elevation contours.

What data can isolines be generated from?

·         Point data (Isometric map-true), Area data (Isopleth map-conceptual). Data for an isopleth map is standardised (same as choropleth just visualised differently).

Isometric map

·         Has lines that connect points registering equal values of an item. Can be made from true point data, continuous/smooth, raw totals or standardised. Such as elevation (contours), precipitation (isohyet), temperature (isotherms), and pressure (isobars).

What kind of colour scheme can isometric maps use?

·         More colour categories than a choropleth map, small gradations are okay.

Isopleth map

·         Conceptual point data, continuous/smooth, uniform within spatial unit, usually standardised. Such as, population density, disease rates, crime rates etc. Internal boundaries can be kept or removed.

What are the interpolation methods?

·         Manual or automated. Automated methods include triangulation, inverse-distance/gridding, or kriging (most accurate and common).

What are some symbolization and design considerations in isarithmic mapping?

·         Lines should be at the forefront, should not have to search for the labels, hypsometric tints (shading between the lines), and a legend for the tints.

What is some base data you could include for a traffic flow map?

·         Roads, transit routes, bus and train, water features, Vancouver municipalities

What does interpolation always involve?

·         Error

Difference between isopleth and isometric

·         In the "isopleth" map, the values are rates or ratios computed for areal units, such as census tracts, whereas in the "isometric" map the values are samples of absolute measurement taken at different points on a map.