c++ - Calculate Camera space coordinates from vtk render -


i have rendered image in vtk, project image points (x,y) 3d camera frame coordinates. each pixel (x,y) have z value in camera frame (obtained z-buffer).

under pinhole projection, standard way be:

x_camera_frame = (x_pixel - cx) * z_camera_frame/ fx;  y_camera_frame = (y_pixel - cy) * z_camera_frame / fy;

where fx , fy focal length , cx cy centre of projection of camera (intrinsic parameters).

the problem is, vtkcamera can set field of view there not way set or focal length or center of projection, how go calculating x_camera_frame , y_camera_frame?

normally center of projection camera position ie. (0,0,0) in camera space. means top left corner of image should @ p = (-imagewidth/2, -imageheight/2, fl), (fl focal length) assuming no further 2d transforms (croping, resizing etc) applied after perspective transform.

p here represents point in image plane seen camera space. convert multiply inverse of projection matrix , should able point in camera space.

i assume know image width , height are. focal length, distance between camera , focal point can used. api returns projection transform matrix, can calculate inverse, before applying image plane point.

arun


Comments

Post a Comment

Popular posts from this blog

matlab - Deleting rows with specific rules -

i got 20*3 cell array , need delete rows contains "137", "2" , "n:t" origin data: 't' '' '' 'np(*)' '' '' [ 137] '' '' [ 2] '' '' 'are' 'and' 'np(fcc_a1#1)' '' '' '1:t' [ 1200] [0.7052] '' [1.2051e+03] [0.7076] '' 'are' 'and' 'np(fcc_a1#3)' '' '' '2:t' [ 1200] [0.0673] '' [1.2051e+03] [0.0671] '' 'are' 'and' 'np(m23c6)' '' '' '3:t' [ 1200] [0.227...
Read more

php - MySQLi multi_query results for later use -

i using mysqli multi_query work several select statemets @ time. know how handle results, able use them later in code. example: <?php //connection stuff $query = "select name, surname database1;"; $query.= "select car, year, type database2 carid='1';"; $query.= "select product, price database3;"; if ($mysqli->multi_query($query)) { if($result = $mysqli->store_result()) { while($row = $result->fetch_row()) { --> here? } } } ?> <html> <div id='persona'> <?php foreach() { --> print name + surname } ?> </div> <div id='cars'> <?php foreach() { --> print car + year + type } ?> </div> <div id='product'> <?php foreach() { --> print product + price } ?> </div> </html> one more thing, prepared statements not possible when using multiple_query, right? there no benefit in putting unrelated queries in 1 multi ...
Read more