Tagged Questions

2
votes
2answers
52 views

How to get angle bewteen two vectors in range -1 to 1 without using arc cosine?

Given two normalized vectors in 3d space, how can I get a value from $-1$ to $1$ based on their angle without using arc cosine? With use of arc cosine, I think this would give me the correct result. ...
2
votes
1answer
75 views

A controlled trapezoid transformation with perspective projecton

I'm trying to implement a controlled trapezoid transformation in Adobe Flash's ActionScript using the built-in perspective projection facility. To give you an idea of how the effect looks like: ...
0
votes
0answers
40 views

scaling items to match field of view (FOV)

I am overlaying some clickable hotspots on top of a proprietary panorama viewer application, and I need to make sure that the hotspots scale according to the changing field of view as the user zooms ...
1
vote
1answer
83 views

Determining camera orientation (possibly using calibration images).

I need to generate a camera calibration pattern. Cameras are expected to be placed at an average height of 15 to 30 feet above ground pointing downwards at roughly 30 degrees. These cameras are ...
0
votes
2answers
108 views

What does negative sine mean in this diagram?

I thought cos was x and sin was y. In quadrant two, cos is negative and sin is positive. Why does this diagram have a negative sign as the x-coord and cos as the y coordinate for q prime's vector? ...
0
votes
0answers
37 views

Find point in $3D$ space only using $3$ rotation inputs and distance

I'm hoping somebody can shed some light on a problem I am trying to solve. As its been a few years out of school my mathematic skills aren't as sharp as they used to be. My problem... In $3D$ space, ...
0
votes
0answers
64 views

Determining a point in 3D space

So given a point, a rotation around the y-axis, a rotation around the x-axis, and a distance, how can one calculate the relative point in space? For example, the beginning coordinates are (0,0,0). ...
0
votes
0answers
168 views

Distance between two objects in a picture

lets say I have a photo that has a picture on a wall and a book upright on the desk. now i know the size of both of these objects. I want to find the distance between two of them on the photo, I was ...
0
votes
1answer
272 views

Find point in 3D space based on start point, three angles and a distance (need example)

I know this has been asked before but the answer wasn't very helpful, sorry. I need an example and to see each step of the equation being solved. Let's say we have 45 degree angles to each axis and ...
0
votes
1answer
202 views

Finding the distance between the centre of an arbitrarily rotated cylinder and a point on that cylinder

this is a bit more complicated than the post title suggests because I was running out of words. I suppose the full title would be: "Finding the distance between the centre of an arbitrarily rotated ...
1
vote
1answer
117 views

Determining angle of tilt from length of axes?

When taking a picture of a cross, if the center of the cross is known, is there any way to determine the angle at which the picture was taken based on the number of points on the y axis above and ...
1
vote
1answer
354 views

Find 3D rotation vector and angle to transform a rectangle into a given quadrilateral

I have a given rectangle that I need to transform into a given quadrilateral shape that resulted from a rotation and translation in 3D space, and subsequent projection. ...
1
vote
1answer
149 views

Finding the radius of a particular center voxel in 3D cylinder-like structure

From the image above, assume that it is a 3D image that is of m*n*o size. Each voxel can only be either 0 or 1. White is 1. Black is 0. In this 3D environment, there is one cylinder-like ...
0
votes
1answer
373 views

Find point in 3D space based on start point, three angles and a distance

I have a start point, {x,y,z} a distance, d and three angles, rotation about the x axis, rotation about the y axis and rotation about the z axis. Each angle is clockwise. How do I calculate the point ...
0
votes
1answer
881 views

Distance from a point to circle's closest point

So let's assume I have a point $P$ in $3d$ space $(x_0, y_0, z_0)$. And I have a circle $C$ that is centered at $(x_1, y_1, z_1)$ with a radius $r$. I need to find the distance from $P$ to the nearest ...