Map Making

First decision—What so you want to show? Thematic maps Center of map First decision—What so you want to show?

#2 What KIND of map to use? Choropleth Proportional symbol Isoline Dot map #2 What KIND of map to use?

Chloropleth map

Proportional symbol map

Isoline map

Dot map

#3 What SCALE to use? Distortion of map increases as scale decreases As scale changes, level of aggregation changes #3 What SCALE to use?

Representative Fraction 1/50,000 1:50,000 Representative Fraction

Verbal Scale “one centimeter to one kilometer” 1 cm=1 km, so 1 cm=1000 m, so 1 cm=100,000 cm Verbal Scale

Graphic Scale

#4 What projection to use? Distortion of direction Distortion of distance Distortion of shape Meridians (longitude, latitude) Shapes (cylinder, tetrahedron, etc) More next class #4 What projection to use?