ISSOM orienteering maps show buildings in plan view. Many buildings edges are orthogonal (i.e. at right angles to each other) – here’s how to draw these buildings neatly and correctly in Adobe Illustrator CS3, and also ensure that parallel building features are lined up correctly.
1. Measure the angle that the building is at, on your basemap:
2. Open up Preferences and go to the General tab. Enter the measured angle in the “Constrain Angle” box:
3. Draw the vertices of the building. Holding down Shift will now constrain subsequent vertices to the constrain angle (and +/- 45 degrees and 90 degrees from it) rather than to the horizontal and vertical of your screen.
4. Using Smart Guides in conjunction with setting the constrain angle will help line up parallel features, allowing buildings to be drawn quickly and accurately. A quirk of switching on Smart Guides, is that you will normally then need to click to reselect any existing node, vertex or partially-drawn building.
Smart Guides are very useful, but can be annoying when drawing very complex buildings with shallow or unusual angles – I typically switch them on or off repeatedly when tracing such buildings, and memorise and jump between two or more constrain angles for different “wings” of the building.
The background imagery used in this example, by the way, is recently released imagery showing the extent of the earthquake damage in Port-au-Prince, Haiti. The OpenStreetMap community is working to quickly complete a map of the city to aid the rescue effort.