Map Use Take a look at your USGS Topo Quad. What spatial reference systems do you see? What spatial reference system is the map printed in? When was the map printed and does it include everything you would expect? What is the declination?

Field Methods 2 When a GPS won’t do: –Forestry canopies –Canyons (no reception or can’t reach) –Underwater

Basic Idea Establish a “station” with more than adequate uncertainty “Shoot” “meets and bounds” to points –Measure direction and distance Convert to coordinates Must use a projected system! –E.g. UTM, State Plane Accuracy decreases with each additional measurement!

A little trig… Existing Coordinate (x1,y1) North dx dy D New Coordinate (x2,y2) Note: This only works in projected systems and there will always be error

Just for fun: Break into groups and try this: –Given: N, W –Direction: 30 degrees –Distance: 1000 meters Where does this put you? Hints: –Use the web to convert DD to UTM –Use a mapping app to find the location

Compass Work North Angles Declination

North is not magnetic north Compasses measure magnetic north (approximately) See: Wiki page at: – nationhttps://en.wikipedia.org/wiki/Magnetic_decli nation –Check out the cool animation on how declination has changed Find out declination at: –

Declination If we measure 0 degrees on a compass, the actually point is off by the “declination”. We must add the declination to all our angles Try it an check on a map

Measuring Distance Best: –Laser distance measuring tool Next best: –A lightweight measuring tape Worst (but works for some situations): –Pacing

Measuring Height You are about to measure the height of redwood trees. How would you do this?