Rajiv K Gupta

US Patent:

58481214, Dec 8, 1998

Filed:

Oct 28, 1996

Appl. No.:

8/738860

Inventors:

Rajiv Gupta - Niskayuna NY
Chukka Srinivas - Malden MA

Assignee:

General Electric Company - Schenectady NY

International Classification:

G01N 2304

US Classification:

378 62

Abstract:

A locally-adaptive method for obtaining sub-pixel registration of mask and opacified digital X-ray images includes the steps of match point generation, locally-adaptive image-to-image warp generation, and log subtraction, for generating a DSA image. Specifically, in match point generation, a set of two-dimensional points in the mask image and their corresponding points in the opacified image are derived. After match point generation, locally-adaptive image-to-image warp generation is performed using the image-to-image match points; that is, a transformation function is generated that maps the matched points in the mask image to their corresponding points in the opacified image. The generated transformation is then applied to the mask image data and the logarithm of the pixel value in the transformed (i. e. , warped) mask image is subtracted from the logarithm of the corresponding pixel value in the opacified image.

US Patent:

55503764, Aug 27, 1996

Filed:

May 22, 1995

Appl. No.:

8/447020

Inventors:

Rajiv Gupta - Schenectady NY
Julia A. Noble - Oxford, GB
Richard I. Hartley - Schenectady NY
Andrea M. Schmitz - Schenectady NY

Assignee:

General Electric Company - Schenectady NY

International Classification:

G01N 2300

US Classification:

2503601

Abstract:

A method of calibrating a linear pushbroom imaging device used in non-destructive testing of a part manufactured according to a CAD model involves identifying the location of fixed reference points, such as tooling balls in the CAD model. Positioning the part on a fixture having tooling balls fixed relative to each other in the same manner as those in the CAD model. Adjusting the part on the fixture such that points on the surface of the part known to be accurate have the same locations relative to the tooling bails as the CAD part is to the CAD tooling balls. Obtaining several projection images of the part and tooling balls at different angles about an axis of rotation passing through the part. Using the known 3D locations of the center of the CAD tooling balls and the corresponding measured screen locations of the is actual tooling balls, transformation matrices, G, M. sub. j may iteratively be determined which map points on the 3D CAD model to 3D points of the part and then map the 3D points of the part to the 2D screen coordinates of each projection image, respectively.

US Patent:

55593348, Sep 24, 1996

Filed:

May 22, 1995

Appl. No.:

8/447021

Inventors:

Rajiv Gupta - Schenectady NY
Richard I. Hartley - Schenectady NY

Assignee:

General Electric Company - Schenectady NY

International Classification:

G01N 2302

US Classification:

2503601

Abstract:

A method of reconstructing selected features of a part manufactured according to a CAD model involves acquiring a set of linear push broom (LPB) projection images of the part acquired at different angles about an axis of rotation passing through the part. Acquiring a set of matrices M. sub. j j=1. . . N, each of which maps 3D coordinates of the part to screen coordinates of one of the projection images. Reconstruction of 3D structures from the projection images requires identification of screen coordinates of each image which correspond to a point of the structure of the part to be reconstructed. Back projecting these screen coordinates modified by the distortion inherent in the LPB imaging device. This is accomplished by selecting a screen coordinate on a feature desired to be reconstructed. Computing a ray passing through the selected screen coordinate through an imaging center.

US Patent:

57151679, Feb 3, 1998

Filed:

Jul 13, 1995

Appl. No.:

8/502034

Inventors:

Rajiv Gupta - Schenectady NY
Barry Joe Webb - Hanson KY

Assignee:

General Electric Company - Schenectady NY

International Classification:

G06F 1900
G06G 764
G06G 766

US Classification:

36447428

Abstract:

A system of accurately positioning a manufactured part in a calibrated position, involves positioning the part on a structure. Adjusting the part on the structure such that points on the surface of the part known to be accurate and drilling notches in the part at known locations. Distances from the surface of the part to the structure in `x` and `z` directions, and a rotation angle. theta. are measured. The part is then placed in a fixture having a nest plate with pins which hold the part by the notches thereby defining an axis through the part. A `z` stop is adjusted to the measured `z` distance which stops rotation of the part about the axis between the pins. An `x` stop is set to the measured x distance which stops translation of the part along the axis between the pins. The nest plate is pivotally attached to the base plate allowing the nest plate to rotate with respect to the base plate the rotational angle. theta. This results in calibrated positioning of the part allowing maximum access to the part.