Photogrammetry has been defined by the American Society for Photogrammetry and Remote Sensing (ASPRS) as the art, science, and technology of obtaining reliable information about physical objects and the environment through processes of recording, measuring and interpreting photographic images and patterns of recorded radiant electromagnetic energy and other phenomena.
An orthographic view is defined as a two-dimensional view of a three-dimensional object with no depth shown.
Simply put, an orthographic map is a top-down 2D view of the earth, much like you’re used to seeing on Google Maps.
A DEM is a ‘bare earth’ elevation model, unmodified from its original data source (such as lidar, ifsar, or an autocorrelated photogrammetric surface) which is supposedly free of vegetation, buildings, and other ‘non-ground’ objects.
A DSM is an elevation model that includes the tops of buildings, trees, powerlines, and any other objects. Commonly this is seen as a canopy model and only ‘sees’ ground where there is nothing else overtop of it.
A DTM is effectively a DEM that has been augmented by elements such as breaklines and observations other than the original data to correct for artifacts produced by using only the original data.
Small 2D projects with minimal data capture requirements can be flown in a matter of minutes once a flight plan has been established. Larger coverage areas, 3D data capture requirements, low altitude flight plans, and separate structures or point of interest capture targets can increase flight time drastically.
On average, we spend around an hour at most job sites once control has been shot and marked.
A Ground Control Point (or GCP) is a georeferenced physical location that provides a means of absolute accuracy for photogrammetry operations. GCP’s are best generated using high-quality surveying equipment and can be permanently marked with a color-capped iron stake, survey nail, etc. Once the shot has been marked, a larger visual target can be painted or placed around it to increase aerial visibility.
Absolute accuracy is the degree to which the measured position of a point on a map corresponds to its actual position in the real world. To have high absolute accuracy a map must have the correct size, shape, and location when compared with the real world.
GCPs are required to make maps with high absolute accuracy.
Absolute accuracy is important when you need to comparing to geo-referenced design documents for a construction project or conducting property boundary surveys. This is also critical for measuring correct elevation values for contour lines.
Relative accuracy is the degree to which the distances between points on a map correspond to the actual distances between those points in the real world. To have high relative accuracy it does not matter where the map is located as long as the size and shape are correct.
GCPs are not required to make maps with high relative accuracy.
Relative accuracy is important when measuring length, area, and volume on your map. This is also critical for correct spacing of contour lines in an aerial topographical survey.
No. We are not a professional land surveying company. While our methods can achieve survey-grade accuracy, our services are merely considered complementary to that of licensed land surveyors. In fact, we have a better shot at producing highly accurate results if we team up with a surveyor to establish our ground control points.
At the end of the day, a licensed land surveyor will always need to inspect and sign off on our data if its intended end-use is as a legally recognized land survey.
Nope, we haven’t had a single crash since we started flying. While our pilot would like to claim it’s all skill, we must also give credit to our equipment maintenance and upkeep routine. We replace wearable parts frequently, and perform test flights after each firmware upgrade to ensure full functionality before we reach the job site.
We carry specialized aerial insurance with higher than normal limits to help mitigate the risk of flying small unmanned aircraft in hazardous areas, and we create an accompanying risk assessment map for each new flight plan.