How To Create 3D Maps And Models
To create a 3D map of a land mass from aerial photos, a camera is mounted on a drone or aircraft and is usually pointed vertically towards the ground. To create 3D map of buildings the camera is mounted horizontally.
Fly overhead camera down, orbit around with camera at 45 degrees orbit lower with camera at 90 degrees.
The drone camera will capture hundreds, even thousands of overlapping photos of the ground, structure or model. The photos will overlap each other, in many instances, the overlap will be 80 to 90%.
The 3D map or 3D model is then created using aerial image stitching photogrammetry software.
The drone will fly using autonomous programmed flight paths called waypoints. To overlap photos of an object or land mass by 80 to 90% would be impossible to complete accurately by pilot navigation. It is essential to have a drone, which has waypoint technology.
Each photo captured will also have it’s GPS coordinates called geotagging saved, which also assists to build the 3D map.
A geotagged photograph is associated with a geographical location. Usually this is done by assigning at least a latitude and longitude to the image. Other fields may be optionally included such as altitude and compass bearing.
What Is The Output From 3D Maps, Models And GIS
Through the use of drone image stitching photogrammetry software and also lidar mapping, there are many products which can be extracted from the aerial imagery. These products include:-
- Point Clouds
- 3D Building Models
- DEM / DTM / DSM (surface models)
- Orthophoto’s (geospatially corrected aerial images)
- Planemetric features (road edges, heights, signs, building footprints, etc)
- Topographic / Terrain / Contour Maps
- Volumetric Surveys
Best Practice
If photos aren’t good, then it’s going to be difficult to get real quality in your 3D models, no matter how good the software is. The photos should be as clear as possible.
Eliminate everything standing in the way of maximum sharpness. This is where more megapixels actually matters. Shooting in RAW will help.
Lighting is always important in photography. Bright, even lighting will allow you to have a small aperture to reduce the image’s depth of field. Shallow depth of field is actually not good for photogrammetry, because blurred details confuse the software.
The goal is to have high detail, sharp, and flat imagery which requires closing up the aperture giving more light. Good lighting will also allow you to lower the ISO, which will reduce grain, and it will allow you to have a high shutter speed which also reduces motion blur.
Give the mapping software only high resolution information.
Filtering out bad or off line photos before the software gets to work, will make the work of the 3D photogrammetry software easier giving higher image accuracy.
If its not in the picture, then it’s not in your mesh and 3D image. Make sure you have the coverage you need to get all the details you want, because it’s difficult to go back and re-shoot in the exact same conditions.
Recent Comments