Region growing is one of the most popular methods for low-level image segmentation. Many researches on region growing have focused on the definition of the homogeneity criterion or growing and merging criterion. However, one disadvantage of conventional region growing is redundancy. It requires a large memory usage, and the computation-efficiency is very low especially for 3D images. To overcome this problem, a non-recursive single-pass 3D region growing algorithm named SymRG is implemented and successfully applied to 3D CT
angiography (CTA) applications for vessel segmentation and bone removal. The method consists of three steps: segmenting one-dimensional regions of each row; doing region merging to adjacent rows to obtain the region segmentation of each slice; and doing region merging to adjacent slices to obtain the final region segmentation of 3D images. To improve the segmentation speed for very large volume 3D CTA images, this algorithm is applied repeatedly to newly updated local cubes. The next new cube can be estimated by checking isolated segmented regions on all 6 faces of the current local cube. This local non-recursive 3D region-growing algorithm is memory-efficient and computation-efficient. Clinical testings of this algorithm on Brain CTA show this technique could effectively remove whole skull, most of the bones on the skull base, and reveal the cerebral vascular structures clearly.
A vision telepresence system was built in our lab, including stereoscopic display on a CRT and a spherical screen. Two images from two cameras are sent to two multimedia video cards (grand-video cards), Ml and Mr. The two cards, Ml and Mr, transform from two video signals of two cameras to RGB signals in its memory. The field synchronism signal of a VGA card is used as a switch, which takes the two RGB signals in Ml and Mr alternately and sends them into a CRT display or a projector for the spherical screen. In fact, the images of two cameras are put into multimedia cards at lower frequency, but are taken from multimedia cards and shown on CRT at higher frequency, the display may be at higher field frequency. The twinkle can be improved. In order to test the depth sense of the stereoscopic display, an experiment was made in our lab. The purpose of the test is to check the effect for the subjects to use the stereoscopic display to recognize the depth of objects. The test result gives some conclusion. (1) The stereo-display-mode (SDM) using 124 mm camera-distance is worse (has bigger depth-error) than the nude-eye-mode (NEM). But the SDM using 226 mm camera-distance is better than the NEM. (2) The 20 m object-distance has bigger depth-error than the 10 m object-distance. And the 30 m object-distance has very big depth-errors
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.