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Questions tagged [photogrammetry]

Photogrammetry is the practice of determining the geometric properties of objects from photographic images.

Photogrammetry is the practice of determining the geometric properties of objects from photographic images. Photogrammetry is as old as modern photography and can be dated to the mid-nineteenth century. Photogrammetry uses methods from many disciplines, including optics and projective geometry.

http://en.wikipedia.org/wiki/Photogrammetry

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How do I reverse-project 2D points into 3D?

I have 4 2D points in screen-space, and I need to reverse-project them back into 3D space. I know that each of the 4 points is a corner of a 3D-rotated rigid rectangle, and I know the size of the rectangle. How can I get 3D coordinates from this? I…
Joshua Carmody
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How can I determine distance from an object in a video?

I have a video file recorded from the front of a moving vehicle. I am going to use OpenCV for object detection and recognition but I'm stuck on one aspect. How can I determine the distance from a recognized object. I can know my current speed and…
Ryan R.
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How would you find the height of objects given an image?

This isn't exactly a programming question exactly. I just want to know what your approach would be to a common problem in Digital image processing. Let's say you have an image of a few trees in say jpg format. How would you go about finding the…
Laz
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OpenCV Orb not finding matches once rotation/scale invariances are introduced

I am working on a project using the Orb feature detector in OpenCV 2.3.1 . I am finding matches between 8 different images, 6 of which are very similar (20 cm difference in camera position, along a linear slider so there is no scale or rotational…
KLowe
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Libraries to get depth map from stereo images?

I'm going to set up some devices to perform real-time 3D motion tracking. My first idea to do so is to use a pair of cameras to take stereo image and calculate the depth map to get the 3D data I needed. Are there any good open source libraries…
Andy Li
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Reprojection of pixels from one image into another

I have a number of calibrated cameras taking a pictures of planar scene. For simplicity let's assume there are 3 cameras. Those cameras are undergoing general motion but mostly translation plus some mild rotation. Example positions of cameras The…
user2080818
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Measure size of object using reference object in photo

I'd like to calculate size of object in a photo which includes both a target object and a reference one. I think what I'd like to do is what this software achieves (I don't know how precise this software…
Light Yagmi
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How do I measure distances in an image?

Let's say we have an image like so (source: curiousexpeditions.org) Let's say we've already used filters and an edge detection algorithm in this pic. Now my goal is to measure distances (NOT actual distances, distance can be in any arbitrary…
Laz
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Determine transformation matrix

As a followup to my previous question about determining camera parameters I have formulated a new problem. I have two pictures of the same rectangle: The first is an image without any transformations and shows the rectangle as it is. The second…
dwergkees
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THREE.JS & Reality Capture - Rotation issue photogrammetry reference camera's in a 3D space

Thanks for taking the time to review my post. I hope that this post will not only yield results for myself but perhaps helps others too! Introduction Currently I am working on a project involving pointclouds generated with photogrammetry. It…
DiabetiMark
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How to know or calculate depth of field of a photo from EXIF tags?

I want to know the depth of field of a photo, preferably in cm or m. I know that we can know the camera setting by reading the EXIF tags, but is there a tag directly telling us the depth of field? Or how can we calculate it from some EXIF…
Andy Li
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Measuring an object from a picture using a known object size

So what I need to do is measuring a foot length from an image taken by an ordinary user. That image will contain a foot with a black sock wearing, a coin (or other known size object), and a white paper (eg A4) where the other two objects will be…
mar
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Measuring height of a playing card deck in an image

I am writing a module for a casino surveillance software. A bit of context: I have several images from a video extracted at different times. I have a reference deck always at a fixed position that I know the size of. Assuming that the distortion,…
PU2014
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Lens correction projection

What is the simplest way to un-warp a photo made using fisheye or wide-angle lens? I'm looking a pixel projection formula that has few parameters. Camera and lens parameters will not be known, so user has to change the parameters visually. Thanks
LicenseQ
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COLMAP photogrammetry: Reconstruction gives only point cloud, no mesh

I've been trying to use COLMAP to produce 3D meshes from photographs, but all I can get is useless point clouds. I've studied various YouTube tutorials, but the results I get differ from what I am seeing, mainly in that I can never get a solid 3D…
Mentalist
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