The words in the quote, in plain English.
Every trade has its shorthand and ours is worse than most. These are the terms that come up when you scope a capture, written for the person signing the invoice rather than the person flying.
Outputs
- OrthomosaicA measurable map made from hundreds of photos
- Hundreds of overlapping aerial photos stitched into one image, then corrected for camera tilt and ground relief so the scale is uniform across the whole picture. That correction is what makes it measurable: distances and areas read true anywhere on it, which an ordinary aerial photo cannot promise. Delivered as a GeoTIFF for your GIS or CAD, plus a web viewer.Mapping and orthomosaic
- DSM and DTMElevation with everything on it, and elevation of bare ground
- A digital surface model (DSM) records the height of everything the camera can see: ground, stockpiles, buildings, trees. A digital terrain model (DTM) is the bare earth with those things removed. You want a DSM for stockpile volumes and a DTM for drainage, grading and cut and fill against a design surface. "DEM" is used loosely for either.Mapping and orthomosaic
- Point cloudMillions of measured points in three dimensions
- A dense set of points, each with a coordinate and usually a colour, describing the surfaces of a site or structure. It is the raw geometry behind a 3D model, and it is what engineers measure on directly. Delivered as LAS or LAZ for your own software.Mapping and orthomosaic
- 360 panoramaA viewpoint you can turn around in
- A full sphere captured from one position, indoors on a monopod or in the air from the drone, viewed in a browser by dragging. Used for elevation views from a floor that does not exist yet, and for walking an interior before the drywall closes.360 aerial panoramas
- Cut and fillHow much earth came out and how much went in
- The volume difference between two surfaces, usually the current ground against the design surface or against last month’s capture. It is how earthworks progress becomes a number rather than an argument at the progress meeting.Mapping and orthomosaic
- As-builtWhat was actually constructed, not what was drawn
- A record of the built condition, ideally captured before it is covered. Overlaid on the design, it shows deviation while there is still time to act, and it is what a facility manager wants at handover.Construction progress monitoring
Accuracy
- GSD (ground sample distance)How much ground one pixel covers
- The size of one pixel measured on the ground, written as cm/px. At 2 cm/px each pixel is a 2 cm square of earth, so a 10 cm crack is five pixels wide and visible; at 8 cm/px it is not. GSD is set by how high the aircraft flies and which camera it carries, so it is agreed before the flight, not after.Mapping and orthomosaic
- GCP (ground control point)A surveyed marker that ties the map to the real world
- A target placed on the ground whose exact coordinates are measured by survey equipment. With several of them across a site, the map lands on the correct real-world coordinates instead of merely being internally consistent. Without them, expect metres of drift: fine for looking, useless for measuring against a design.Mapping and orthomosaic
- RTKCentimetre-level positioning on the aircraft itself
- Real time kinematic positioning corrects the drone’s own GPS against a fixed base station, so each photo is tagged to within centimetres. It reduces how much ground control a job needs, though checkpoints on the ground are still what proves the result.
- Relative and absolute accuracyRight against itself, or right against the world
- Relative accuracy is how well points on the map relate to each other: measure a building and the dimension is correct. Absolute accuracy is how well those points match real-world coordinates: put the map on your site plan and it lands where it should. Volumes need the first. Anything that touches a design surface, a property line or a permit needs the second, which needs ground control.
Capture methods
- PhotogrammetryBuilding 3D from overlapping photographs
- Software finds the same features across hundreds of overlapping photos and works backwards to where the camera was and where the surfaces are. It is the cost-effective way to get an orthomosaic, a surface model and a textured 3D mesh, and it is what most construction, development and inspection work uses.Mapping and orthomosaic
- LiDARMeasuring with laser pulses instead of photographs
- The sensor fires laser pulses and times their return. Because some pulses slip between leaves and reach the ground, LiDAR gets bare-earth elevation under vegetation, which photogrammetry cannot. It costs more and produces no imagery, so it is the right tool for forested corridors and flood modelling rather than an everyday site map.
- Thermal imagingSeeing heat rather than light
- A radiometric thermal camera reads surface temperature per pixel. Wet insulation under a roof membrane holds heat longer than dry insulation, and a failing solar cell runs hotter than its neighbours, so both show up as patterns invisible in daylight. Timing matters: roofs are flown after sunset, solar in bright midday sun.Solar and utility inspection
- Reality captureA dated, located record of what is actually there
- Photos, 360 walkthroughs, maps and models organised by where and when they were taken, so the site can be revisited as it was on a given date. The value is not any single image; it is that the record is systematic enough to settle a question two years later.Interior 360 site walks
- Nadir and obliqueStraight down, and at an angle
- Nadir images point straight down and are what an orthomosaic is built from. Oblique images are taken at an angle and are what let a 3D model show building facades rather than just roofs. Most jobs fly both.
- Overlap and sidelapHow much each photo repeats the last
- The percentage of each image that also appears in the next one along the flight line (overlap) and in the neighbouring line (sidelap). Typically 80 percent of each. Too little and the software cannot stitch; too much and the flight and processing take longer than they need to.
Platforms and process
- Advanced RPAS certificateThe Transport Canada licence for the flights that matter
- The certification required in Canada to fly in controlled airspace and near people, which covers most commercial sites. The basic certificate does not allow either. Every operator Lensdrone dispatches holds the advanced one.
- SFOCSpecial permission for operations outside the standard rules
- A Special Flight Operations Certificate from Transport Canada, needed for flights above 122 m, beyond visual line of sight, or over people in ways the standard rules do not cover. It takes lead time to obtain, which is why it is identified at scoping rather than discovered on the day.
- Mapping is not surveyingWhere the line sits, and why it matters
- A legal land survey (boundaries, legal descriptions, plans of subdivision) can only be produced by a licensed land surveyor. Drone mapping produces measurable imagery and models with a stated, checked accuracy, which is a different thing. Lensdrone delivers the second and works alongside your surveyor for the first; any provider advertising "survey-grade" results without a licence is worth a second look.Mapping and orthomosaic
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