The hook
PS-side topo work covers standards, QA/QC, and equipment selection across the full spectrum: ground survey, aerial photogrammetry, lidar, hydrographic / bathymetric. Choosing the right method for the site is half the value.
| Method | Best for | Accuracy + caveats |
|---|---|---|
| Total station + rod | Small sites with hard features | ~1 cm; slow but precise |
| RTK GNSS rover | Open sites, mid-size | ~2-5 cm; needs sky |
| Drone photogrammetry | Large open sites, exposed surfaces | ~5-10 cm with GCPs; misses under-canopy |
| Drone LiDAR | Vegetated sites, complex 3D | ~3-5 cm; expensive sensor |
| Manned aerial mapping | Wide-area corridors | ~30 cm contours; cost-effective at scale |
| Hydrographic single-beam | Lakes, rivers — depth profiles | ~10 cm vertical; one ping at a time |
| Hydrographic multibeam | Harbors, navigation channels | ~5 cm vertical, full bottom coverage |
Memorize these
Concepts that show up on the exam
NMAS / ASPRS
National Map Accuracy Standards (older) and ASPRS (modern) define horizontal and vertical accuracy at confidence levels.
Hydrographic terms
Sounding = depth measurement. Tide correction = adjusting soundings to a vertical datum (often MLLW). Bathymetric = water-depth-focused topo.
Utility nomenclature
Standard symbology for above- and below-ground utilities. SUE Quality Levels A-D for subsurface confidence.
Test yourself
How well did it stick?
A quick 5-question check on Topographic Surveys. See where you stand and what to review.