Lead’Air’s Unique Understanding of Oblique Imagery
Conventionally oblique imagery is achieved by simply tilting the camera in one direction, say to the right. The tilt angle is normally 45 degrees, although there is no rule. Depending on the lens the image covers for example from 30 to 60 degrees in the case of a 30 degrees view angle. Therefore, the camera is seeing the facades of all buildings from different angles which is the foundation of 3D city mapping.
Lead’Air has extended the traditional oblique model by combining several rotations; so instead of tilting the camera only in on direction, we tilt the camera in two directions or even three directions, as needed. For example, we roll the camera to the left and at the same time pitch it forward. In addition, we apply a rotation around the optical axis. The angles are as needed to achieve the coverage that we want to obtain, for example 20 degrees roll, 20 degrees pitch, 6 degrees yaw rotation as in the MidasDUO example below:
Below, the same drawing as above shown in 3D:
The drawing below represents two opposite MidasDUO lines planned with 70% lateral overlap. This shows that after only two passes the camera has already captured a complete 360 degrees coverage from nadir 0 degrees to 45 degrees and above. The coverage above 60 degrees which is looking too far to be useful in the 3D model is omitted. We can compare the way this system works to a 180 degrees scan.
Two lines flown in opposite direction generate a full 360 degrees coverage which is already capable of to be processed as a 3d model!
This implies that for this system to work the lines have to be flown one after the other in opposite direction, which is anyhow what survey airplanes do most of the time.
One can see in the drawing above that even with only two cameras the MidasDUO system generates a solid 360 oblique coverage between 0 and 60 degrees. Every point on the ground is recorded multiple times from different perspectives. There are no advantages to use a higher number of cameras other than to increase the width of strip coverage and therefore reduce the numbers of lines and the cost of the project. But for small project with less than 100 lines, the metaDUO does the same job at a fraction of the cost.
The New Lead’Air MIDAS Oblique Camera System
Based on the above, Lead’Air has redesigned in 2022 the MIDAS 3D aerial camera systems this new unique technology which can be described as a forward looking semi cardinal oblique camera system. Contrary to all existing oblique systems whose cameras are looking 90 degrees away from each other’s and in opposite direction, the new MIDAS cameras are overlapping cameras which are orientated in the same general directions, generating a 180 degrees coverage from left to right via forwards.
Instead of individual cameras collecting four separate perspectives, the new MIDAS collects a single perspective. The Midas systems treats data collection as a complete cone, instead of five separate image cones. The collective perspective of the Midas cameras enables the complete coverage of objects from all possible azimuth angles above 45 degrees when covered with multiple flight lines, instead of from just five separate perspectives which become redundant after two or three images (since all the perspectives are coming from the same viewpoint).
Less Cameras Needed
As we have demonstrated above, the single cone collection technique has the advantage that it allows reducing the number of cameras without affecting the quality of the results. For example, the MidasDUO which has just two cameras, resulting in a system that is affordable, small, light, and easy to handle or the MidasTRIO which provides a wider coverage. Why go to the trouble of doing that? Medium cameras are expensive, and the more cameras used, the more expensive the system becomes to buy and operate. In short, if a project can be flown with a $145,000 MidasDUO, why use a million dollars camera to fly it?
Changing From One New Midas Configuration to Another
Example converting a MidasTRIO into a MidasDUO
The New Midas system has been designed so that the user can easily and rapidly convert his New Midas from one configuration to another. It is therefore possible to start with a MidasDUO (two cameras), then add one camera to create a MetaTRIO, and if this is required to add yet another camera to collect vertically (see following paragraph about vertical camera). In fact, one can rearrange the array of cameras in more than half a dozen configurations
- MidasDUO Landscape and portrait
- MidasDUO Landscape and portrait with nadir
- MidasTRIO Landscape and portrait
- MidasTRIO Landscape and portrait with nadir
- Midas6PACK portrait
This allows the user to optimize the number of cameras which he owns, for example one can configure a total of 6 cameras as 3 metaDUO or as 2 MidasTRIO depending on the type of mission which must be flown.