Link to the University of Pittsburgh Homepage
Link to the University Library System Homepage Link to the Contact Us Form


Tamburo, Robert Joseph (2002) GRADIENT-ORIENTED BOUNDARY PROFILES FOR SHAPE ANALYSIS USING MEDIAL FEATURES. Master's Thesis, University of Pittsburgh. (Unpublished)

PDF (Gradient-Oriented Boundary Profiles for Shape Analysis Using Medial Features)
Primary Text

Download (10MB) | Preview
[img] Video (AVI) (Tamburo-hollowsphere)
Supplemental Material

Download (11MB)
[img] Video (AVI) (Tamburo-sphere)
Supplemental Material

Download (8MB)


Gradient-oriented boundary profiles have been developed as a novel method to parameterize boundaries. Boundary profiles are created at locations of high gradient magnitude by averaging intensity within a neighborhood of voxels oriented along the image gradient, making them rotationally invariant and relatively insensitive to image noise. A cumulative Gaussian is fit to the collection of averaged voxel intensities yielding estimates of (1) extrapolated intensity values for voxels located far inside and outside of a boundary and (2) anatomical boundary location. Intrinsic measures of confidence have been developed to eliminate low-confidence parameter estimates. Thresholds placed on these measures of confidence allow for high-confidence unsupervised classification of boundaries. The validity of gradient-oriented profiles is demonstrated on artificially generated three-dimensional test data and shown to accurately parameterize and classify the boundary. Applying the measures of confidence and establishing thresholds, the accuracy of boundary location and intensities estimates improved drastically, making them a high-quality replacement for simpler methods of boundary detection. Towards shape analysis, gradient-oriented boundary profiles are applied to an existing a medial-based approach to shape analysis, known as core atoms. Core atoms in their previous implementation were based on simple gradient direction and unable to form without a priori knowledge of object intensity relative to background. Boundary profiles were applied to core atoms permitting the formation of so called "core profiles". Core profiles remove any restriction on the object's or the background's intensity, allowing multiple objects of differing intensities to be located with a single application.Core profiles were applied to 3D computer-generated data, as well as RT3D ultrasound cardiac phantom data. It was shown on computer-generated data that calculating the volume with core profiles is more accurate then calculating the volume with core atoms, because of the improved accuracy of the boundary location. Two new methods of automatically measuring volume on non-parametric data with core profiles are proposed. Future work with includes constructing medial node models improved by gradient-oriented boundary profiles for automated left ventricular identification and measurement.


Social Networking:
Share |


Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Tamburo, Robert Josephrjtst21@pitt.eduRJTST21
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairStetten,
Committee MemberLi, C. Cccl@ee.pitt.eduCCL
Committee MemberSclabassi, Robert
Date: 20 December 2002
Date Type: Completion
Defense Date: 25 November 2002
Approval Date: 20 December 2002
Submission Date: 8 December 2002
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Bioengineering
Degree: MSBeng - Master of Science in Bioengineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: boundary parameterization; core atoms; core profiles; gradient-oriented boundary profiles; medialness; real-time three-dimensional ultrasound
Other ID:, etd-12082002-204455
Date Deposited: 10 Nov 2011 20:09
Last Modified: 15 Nov 2016 13:53


Monthly Views for the past 3 years

Plum Analytics

Actions (login required)

View Item View Item