No one has been on at all this week. Is sumthing up?

I started on the GM project. It has now surpassed GDN's best day in traffic. I offered to register GM 7 for those who would help me get it going, but no one took the offer. —hartnell

Its a common era that site gets bit quiet time to time. ;)

Personally im working with source of yaBasic. Not with good succes tho. Also next issue of PCopy keeps me busy (beside of real life too)

E.K.Virtanen

www.ascii-world.com

Busy at school. My group is 3 weeks behind project schedule, although we have just yesterday cracked the stupid nut that was keeping us stuck for 3 weeks, and are now gaining in on the damn time-line again :)

Our problem was calculating the position of a video camera relative to the object it is viewing based only on what the video camera sees. 3D position and orientation. It's fun to work with when one makes progress :)

… my … brain … hurts … thinking … about … that … kind… of … math… help … brain … going … to … explode …

:)

—hartnell

Mine too, at first. But actually it is almost like simple algebra. One just needs to set up an equation system that needs to be solved. I'm sure many around here are able to solve two equations with two unknowns. Finding the camera position basically just becomes solving maybe 8 equations with 8 unknowns. Sure it's a lot more work, but the principle is the same :)

I show the camera a pattern of points, then i define some points on the patterns as being at some specific location in 3D space, e.g. the first point on the pattern could be at location 0,0,0 the second at 1,0,0 etc. Objects are projected into the camera frame (image) with the equation:

(1)Where $x'$ is the point in the image, $X$ is a 3D location (these i define), and $P$ is the camera matrix (see also projection) which both includes the camera's 3D position and its orientation. I "just" need enough points to solve $P$ because i know $X$ and $x'$.

That sounds easy enough, but of course there is noise in the image, so what is on the image won't be perfect coordinates. The points are also quantized to the screen resolution which also adds noise, so in reality the equations are solved using singular value decomposition and some smart way of excluding outliers (points which have too much noise and only degrade the estimation of $P$).

This was just a little reading for those that are bored :) Btw, the reason we were stuck was not in estimating the position of the camera itself because this was actually just a function call in the OpenCV library, but we couldn't make sense of the coordinates it provided. Another problem we had was actually to find the 3D points in the camera image. Suffice to say it took a long time to find although it shouldn't have.

I visit here daily, often few times every day but here is not much for me :-/

Mostly because of peoples here talks nearly allways about windows programming languages and 2D or 3D graphics which wont interest me :)

But cool place, love it.

E.K.Virtanen

www.ascii-world.com

hey we are here and we will find something to speak about