Topics & Glossary

Base / rover

Reference GNSS receiver on a known point vs moving receiver—core to RTK/PPK. Dictionary

CRS

Coordinate reference system: datum, projection, units, and axis order (often cited by EPSG code). Dictionary

DTM / DSM

Digital terrain model (bare earth) vs digital surface model (includes tops of objects). Dictionary

GNSS

Global Navigation Satellite System—GPS, Galileo, GLONASS, BeiDou, etc. Survey workflows add RTK, PPK, or network RTK. Dictionary

GSD

Ground sample distance—pixel size on the ground for imagery or orthos. Dictionary

LAS / LAZ

Standard point cloud file formats for LiDAR; LAZ is compressed. Dictionary

Multipath

GNSS signal reflections that degrade position—common near buildings and metal. Dictionary

PPK / RTK / network RTK

PPK post-processes GNSS in the office. RTK applies corrections in real time. Network RTK uses a service (often NTRIP / VRS) instead of your own base. Guide · Dictionary

Point cloud

Large set of XYZ points with optional attributes—from LiDAR or dense matching. Dictionary

Precision vs accuracy

Repeatability vs closeness to true value—both matter in specs and QA. Accuracy guide · Dictionary

RMSE

Root mean square error; common statistic for comparing checkpoints to control. Dictionary

RTCM

Standard binary messages carrying GNSS corrections (often over NTRIP). Dictionary

SLAM

Simultaneous localization and mapping—build a map and track pose from sensors, often with loop closure. Guide · Dictionary

Full dictionary (A–Z) · Learn overview · About GeoSurveyHub