The 4 Key Components to Photogrammetry Capture

Location, stillness, camera settings and camera movement

Whether you are in a controlled or uncontrolled environment, there are four key components for successful photogrammetry capture: location, stillness, camera settings and camera movement. Paying close attention to these will help reduce tiling, blurring and other issues when scanning photogrammetry objects.

Location

lighting, shadows, refraction and reflections

Example in Photoscan of a model with far too many artifacts, or elements of their environment that intertwined with the model as the point cloud processed.

During the post-processing of a photogrammetry model, most of the cleanup necessary is due to bad lighting conditions present while shooting in the field. Strange white or gray clumps, often referred to as “artifacts”, might be affixed to your subject. These appear because the software couldn’t differentiate lights or shadows occluded by your subject. The best way to minimize these artifacts is to capture your subject with adequate lighting (which minimizes shadows), while avoiding refractive or reflective surfaces. This is a crucial part of the production process that will save you significant headaches in generating the models.

  • Always capture subjects in the brightest area in which you can reasonably position them. Don’t select an area where there will be any lights visibly facing the camera’s lens.

  • If you are taking individual photos, you may be able to fully eclipse a visible light with your subject, but this still isn’t advised.

  • Try to light your subject as consistently as possible on their front, back, top and sides, but if you have to pick, position your subject towards the best lighting so their face is well measured. Avoid any hard lights above hair that will reflect/sheen light into the camera.

  • Make sure that your subject does not stand too close to any walls or surfaces that will clearly present their shadow in the frame. When the software identifies a wall that is one color, and a shadow that is a shade between the color of the wall and the subject, it will often try to attach the subject to the wall with the shadow as a transition.

  • Beware subjects that include refractive or reflective surfaces (like thick or mirrored glasses). These materials will reflect light differently than your subject from one photo to another, and will cause subtractive and warping artifacts on your subject.

TL;DR If you can see a light bulb or your subject’s shadow in the frame, if your subject has more lighting on one side of them than another, or if the lighting seems at all dim, try to move somewhere brighter.

Stillness

a consistent and motionless subject, with nothing in the foreground

Photogrammetry excels at making 3D models of a motionless object, so if you’re trying to make a model of something that can move, like a person, advise them and monitor that they do not move. If such direction for your story would violate ethical standards of photojournalism then plan ways for the project to adhere to standards accordingly.

  • Tell your subjects: “Don’t move at all…but blinking is okay.” If you have an assistant who can observe them, they should watch for any twitches, or subtle arm movements. Subjects striking a pose are especially prone to movement. Over 10-20 seconds, it is likely that their arms and posture may barely slump, which may cause distortion.

  • If someone moves more than a twitch, stop recording and start over. Kindly point out why you’re starting over so they understand that don’t move means do not move.

  • Give the subject a specific focal point in the distance from where they are already looking. Moving eyes generally lead to minor head movements.

  • When using a sweeping video to capture, minimize the objects that cross between you and the subject. Objects that cross between you and the subject impede capture and impair modeling especially.

  • Even in an uncontrolled environment such as a convention, try to setup a momentarily controlled perimeter that only you will walk within during your capture.

TL;DR Tell them not to move. Make sure they don’t move. When they move, start over.

Camera settings

lock camera focus, aperture, and white balance

Photogrammetry works best when capturing a consistently formed and colored reality. Thus, don’t change your settings from shot to shot.

Keep your focus as sharp as possible and as deep as possible (prioritizing your subject). Regardless of using a DSLR or smartphone, set your focus before each recording, and if possible lock your focus so that it doesn’t shift from one position to another.

  • Use a consistently wide focal length (do not zoom). Changes in focal length distort the triangulation photogrammetry softwares do, because now the pixels are moving more or less from one frame to another than they were.

  • Set and lock a white balance for your capture or else your subject is going to have distorted colors from one area to another. If you don’t lock your white balance while using a smartphone camera, it will often change its color balance automatically.

  • While there are ways to do it, changing the exposure from one frame to another will often lead to an inconsistent color palette, and may even cause the software to not recognize that two frames are related to each other.

TL;DR Before starting capture on a new subject, always set and lock your focus and other settings. Then don’t touch them again until you are completely finished with that subject.

Camera movement

be intentional, consistent, predictable and quick.

While you need to capture your whole subject, it’s as important that your capture is understood by the photogrammetry software. And if you don’t want hours of rendering, or a wavering subject, capture quickly.

  • Plan your movement, communicate your movement to your team, and avoid deviations.

  • When capturing a whole person, make a safe 15-foot radius. You need to keep your eyes on your screen and not on where you’re walking.

  • If your subject is concerned with where you are walking, they will move to look at you.

  • You may need a larger or smaller radius depending on the subject’s height and pose.

  • Do close-ups second; it’s easier to shorten your radius than expand it. Also, move in closer, don’t zoom.

  • Don’t make your radius larger than necessary. The wider your orbit, the further your walk, the longer you take, the more frames you have.

  • Plan to move quickly. For most computers you want to keep your project to less than 400 images (our goal was 375).

  • If you are capturing a subject using video (suggested), that’s only 13 seconds total for your project.

  • You may be able to stretch to 26 seconds of capture by compressing time (dropping frames) in Premiere, but the more frames you drop, the harder the photogrammetry software has to work to triangulate larger changes from frame to frame.

  • Don’t speed up or slow down; keep the difference between frames consistent.

  • If there is an important area of the subject, such as their face, don’t do it slower, just do a 2nd closeup sweep.

  • Photogrammetry doesn’t require a steadicam. Don’t worry about minor camera shake. Blur isn’t helpful, but if you didn’t lose focus, you’re probably fine.

  • If your subject has nothing that could move, like a statue, you should keep the subject at the center of your frame and orbit it for a complete 360-degrees.

  • Feel free to do additional orbits/sweeps for closeups as necessary

  • If your subject has elements that could move, like a person or tree, it’s advised that you only orbit around the subject for between 270-300 degrees.

  • This way the camera’s field-of-view has captured all surfaces of the subject with a minimal amount of overlap. We minimize overlap on moving subjects due to the likelihood the subject will have fractionally shifted from the beginning to the end.

  • When the software tries to stitch together areas of shifted overlap, it often causes a noticeable crack or scar along the stitching seam.

  • Due to the likelihood of a stitching scar, we suggest starting and ending the capture of a person from behind so that the scar doesn’t run down their face.

  • You can do additional orbits/sweeps for close-ups, but you will want to make sure your subject knows you’ll do multiple sweeps ahead of time, because they can’t drop the pose from the end of your first to the start of your second. Be quick and be intentional.

  • If you are orbiting clockwise, don’t suddenly shift counterclockwise, or vice versa. Such an unpredictable shift will often cause the software to no longer recognize anything after that movement as related to before it.

  • If you think you may have done so, just start that entire movement over.

  • Maintain one direction of camera movement per sweep. Don’t move up, down, left, right, in or out, serpentining around your subject in a single recording. If you want different orientations and movements, make them separate recordings.

Ex.: Record a portrait-orientation wide-shot clockwise orbit along the subject’s beltline, then stop recording. Position yourself closer with a slight downward tilt, then record a 2nd close-up clockwise sweep of the subject’s head.

Have a partner immediately check your video. If you kept to the above-mentioned 13-26 seconds, this is a brief sacrifice before you face an hour of worthless rendering.

If your partner sees any movement that violates the above, do it again. A re-shoot only lasts 13-26 seconds.

TL;DR Have a plan, communicate, move quickly, safely and consistently, and when in doubt, retake.

Overall best practices TL;DR:

  1. Pick a well-lit place, and set up a safe perimeter.

  2. Tell your subject to look somewhere specific and stay still.

  3. Stand behind your subject’s right leg; lock your focus and other camera settings on the subject.

  4. Record them while walking around the front of the subject, ending behind their left leg.

  5. Review your footage and retake as necessary.

About the authors

Henry Keyser

VR Journalism Student; focusing on media innovation, product management, TV Producing. Also a relapsing playwright.

Theodore Chryssos

Lifestyle journalist studying marketing communications, emerging-media geek, VR acolyte, amateur videographer, stationery enthusiast.

Jessica Buchleitner

Author of the 50 Women anthology series and Co-lead Editor/Producer Stories from Girls and Women of Mogadishu. United Nations delegate now obsessed with committing acts of journalism using virtual and augmented reality.

About the project

Photojournalism in 3D for VR and Beyond

In this project, students will use modern approaches to making 3D images both with hardware and software processing.

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