High-Speed Range Estimation Based on Intensity Gradient Analysis

Skifstad, Kurt D.

doi:10.1007/978-1-4612-3112-7

Cited by 9 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is easy to show by means of counter examples that, in general, this technique fails to obtain the true NED. However, this approach has been proposed in the field of Automatic Speech Recognition [l], [4] as an (empirically better) alternative to the conventional Dynamic Time Warping procedure usually adopted for "paring acoustic sequences of speech [lo] [8]. As adapted to our NED problem, this suboptimal a p proach can be implemented as shown in Fig.…”

Section: -7mentioning

confidence: 99%

Fast computation of normalized edit distances

Vidal

Marzal

Aibar

1995

IEEE Trans. Pattern Anal. Machine Intell.

View full text Add to dashboard Cite

As explained in Section III.A, the computations for all rows of the image can be performed in parallel. Thus, the computations for a 512 x 512 image, with 512 processors operating in parallel, can be completed in 512 clock cycles. The critical path consists of an absolute difference module followed by a comparator. The Verilog-XL simulation results show that it is possible to operate the implemented circuit with a 11 ns clock. Since new inputs can be provided to the system every 11 ns, a 512 x 512 image can be processed in 5.632 , US. At 50 frames per second a new pixel value is input to the system every 73.6 ns. Since the minimum clock period is 11 ns, this input [7]

show abstract

Section: -7mentioning

confidence: 99%

Fast computation of normalized edit distances

Vidal

Marzal

Aibar

1995

IEEE Trans. Pattern Anal. Machine Intell.

View full text Add to dashboard Cite

show abstract

“…The accuracy of the depth measurements is low. Errors in the range of 15-30 percent were reported in the experiments [7].…”

Section: Stg Algorithm For 3d Structure Estimationmentioning

confidence: 94%

“…For any such sequence, the magnitude of the temporal gradient is less than the magnitude of the spatial gradient, if it has displaced less than the specific disparity value [7]. When the magnitude of the temporal gradient is greater than or equal to the magnitude of the spatial gradient, it is implied that the sequence has undergone a image displacement equal to the specific disparity value.…”

mentioning

confidence: 99%

Acquisition of 3D structure of selectable quality from image streams

Dalmia

Trivedi

Proceedings of 1994 IEEE Workshop on Applications of Computer Vision

View full text Add to dashboard Cite

In this paper we present a computational approach for extracting three-dimensional structure of controllable resolution, depth of field, and accuracy, all made available at real-time speeds. This approach utilizes the spatial and the temporal gradients of the streams of images acquired using an actively controlled camera. Depending on the requirements of a particular task, appropriate parameters such as disparity value sought , the inter-frame camera displacement, and number of frames in a stream, are chosen to control the resolution, depth of field, and accuracy. The acquisition and processing of the image stream are done in real-time on a pipeline architecture based processor. Extensive experiments are presented to demonstrate the accuracy, controllability of depth of field and resolution, and ability to perform successfully in a variety of scenes. The system operated with no latency between the image acquisition and processing. The total acquisition and processing time in these experiments is in the range of 0.27 to 1.56 sec. The depth results have an accuracy of 85% to 92%. 0-8186-6410-X/94 $4.00 Q 1994 IEEE

show abstract

“…Both the correspondence problem and optical ow calculation have proven to be di cult in terms of reliability and implementation. We therefore look to methods which directly utilize image brightness information to recover motion 20,21,22,23]. These methods lead to computations in the image domain rather than symbolic or sequential computations.…”

mentioning

confidence: 99%

An analog VLSI chip for estimating the focus of expansion

McQuirk

Lee²,

Horn³

1997 IEEE International Solids-State Circuits Conference. Digest of Technical Papers

View full text Add to dashboard Cite

For applications involving the control of moving vehicles, the recovery of relative motion between a camera and its environment is of high utility. This thesis describes the design and testing of a real-time analog vlsi chip which estimates the focus of expansion (foe) f r o m measured time-varying images. Our approach assumes a camera moving through a xed world with translational velocity the foe is the projection of the translation vector onto the image plane. This location is the point t o wards which the camera is moving, and other points appear to be expanding outward from. By way of the camera imaging parameters, the location of the foe gives the direction of 3-D translation.The algorithm we use for estimating the foe minimizes the sum of squares of the di erences at every pixel between the observed time variation of brightness and the predicted variation given the assumed position of the foe. This minimization is not straightforward, because the relationship between the brightness derivatives depends on the unknown distance to the surface being imaged. However, image points where brightness is instantaneously constant play a critical role. Ideally, the foe would be at the intersection of the tangents to the iso-brightness contours at these \stationary" points. In practice, brightness derivatives are hard to estimate accurately given that the image is quite noisy. Reliable results can nevertheless be obtained if the image contains many stationary points and the point is found that minimizes the sum of squares of the perpendicular distances from the tangents at the stationary points.The foe chip calculates the gradient of this least-squares minimization sum, and the estimation is performed by closing a feedback loop around it. The chip has been implemented using an embedded ccd imager for image acquisition and a row-parallel processing scheme. A 64 64 version was fabricated in a 2 m ccd/bicmos process through mosis with a design goal of 200 mW of on-chip power, a top frame rate of 1000 frames/second, and a basic accuracy of 5%. A complete experimental system which estimates the foe in real time using real motion and image scenes is demonstrated.

show abstract

High-Speed Range Estimation Based on Intensity Gradient Analysis

Cited by 9 publications

References 0 publications

Fast computation of normalized edit distances

Fast computation of normalized edit distances

Acquisition of 3D structure of selectable quality from image streams

An analog VLSI chip for estimating the focus of expansion

Contact Info

Product

Resources

About