kinect object measuring

I am currently trying to figure out a way 开发者_运维问答to calcute the size of a given object with kinect

since I have the following data

angular field of view of the lens distance and width in pixels from a 800*600 resolution

I believe this can be possible to calculate. Does anyone has math skills to give me a little help?

With some trigonometry, it should be possible to approximate.

If you draw a right trangle ABC, with the camera at one of the legs (A), and the object at the far end (edge BC), where the right angle is (C), then the height of the object is going to be the height of leg BC. the distance to the pixel might be the distance of leg AC or AB. The Kinect sensor specifications are going to regulate that. If you get distance to the center of a pixel, then it will be AC. if you have distances to pixel corners then the distance will be AB.

With A representing the angle at the camera that the pixel takes up, d is the distance of the hypotenuse of a right angle and y is the distance of the far leg (edge BC):

sin(A) = y / d

y = d sin(A)

y is the length of the pixel projected into the object plane. You calculate it by multiplying the sin of the angel by the distance to the object.

Here I confess I do not know the API of the kinect, and what level of detail it provides. You say you have the angle of the field of vision. You might assume each pixel of your 800x600 pixel grid takes up an equal angle of your camera's field of vision. If you do, then you can break up that field of vision into equal pieces to measure the linear size of your object in each pixel.

You also mentioned that you have the distance to the object. I was assuming that you have a distance map for each pixel of the 800x600 grid. If this is incorrect, some calculations can be done to approximate a distance grid for the pixels involving the object of interest if you make some assumptions about the object being measured.