Birds Eye Photomontage

This project involved the use of a drone to shoot a wide angle picture, which we later used for a photomontage. Rhino is a really good tool for this kind of work since it allows us for precise adjustments of the virtual cameras position, FOV, tilt, aspect ratio and target point.
the building is a hospital extension and was done for one of our local german clients using Octane for Rendering and Photoshop for PP.

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Awesome render! Any chance you could give a quick over view of your perspective matching process? I do some rendering, but compositing into an existing photo has always been a mystery to me!

The key is to recreate the camera you used to shot the photo in Rhino.
This might seem trivial, however there are many mistakes that can happen along the way.
Let’s start with…
1. Camera / Target Position. It is crucial that you document the cameras position and the direction of the target point as precise as possible, because doing so will dramatically reduce any guesswork later on.
As long as you are terrestrial, this isn’t a huge problem, you use a tripod and adjust the camera precisely the way you want, make sure to take several photos of your camera tripod with your smartphone, so you can see it in its direct near environment, also make sure to mark the camera´s position exactly on a site plan or even better a hires orthophoto, a google map screenshot might possibly be enough. Try to use easy identifiable visual references for the camera position (manhole cover, street lights, trees…), if necessary take measurements to these points to recreate the camera position later in CAD.
The same is true for the camera target, if possible line it up horizontally with a structure you can later easy identify on the orthophoto, this is especially important if you cannot point the camera directly to such a structure (the center of your picture is always the point where the camera vector is intersecting with the physical world).

1.1. When you do not have a high quality orthophoto and you own a drone with an gimbal that can turn 90 deg down, this is a great alternative. Simply fly the drone exactly over your tripod at about 2 meter height. Then increase the altitude of the drone until you can see your tripod together with the significant surroundings, take a photo for referencing the xy camera position in CAD later on.

1.2. When you actually use a drone to shot the footage for the photomontage, the localisation becomes more challenging.
a) always do a second photo with the gimbal turned 90 degrees down. This way you can document the drones XY position in relation to surrounding structures.
b) If you cannot see structures e.g. due to low altitude, stay on the spot and increase altitude until you do. For certain situations (like strong winds…) it can also help to mark the XY position of the drone shot with a tripod or something similar. Just move exactly under your hovering drone and place your marker between your feet.
c) to further improve the precision you will get from the drones gps and altitude sensors, you can use a laser range finder for outdoor use and measure the altitude of the drone by placing the laser exactly unter the drone on the ground. Mind that this can not be done under all circumstances. Eventually you can also try triangulation if you have a helping hand.

2. Creating the Virtual Camera
… to be continued

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