Motion analysis through geometry correction and warping
View Patent ↗An object in a hot atmosphere with a temperature greater than 400 F in a gas turbine moves in a 3D space. The movement may include a vibrational movement. The movement includes a rotational movement about an axis and a translational movement along the axis. Images of the object are recorded with a camera, which may be a high-speed camera. The object is provided with a pattern that is tracked in images. Warpings of sub-patches in a reference image of the object are determined to form standard format warped areas. The warpings are applied piece-wise to areas in following images to create corrected images. Standard tracking such as SSD tracking is applied to the piece-wise corrected images to determine a movement of the object. The image correction and object tracking are performed by a processor.
1. A method to track a 3D object in a plurality of images, comprising: providing a predetermined pattern on the 3D object;
identifying a patch containing at least part of the predetermined pattern on the 3D object in a reference image in the plurality of images;
determining a plurality of sub-patches in the patch;
for each of the plurality of sub-patches in the patch, warping a captured part of the predetermined pattern to a standard format image shape;
determining an image area inside the patch in a second image;
applying the warping by a processor to image data of the second image inside the patch; and
determining by the processor a movement of the 3D object from the reference image and the second image.
2. The method of claim 1 , wherein the movement is determined by applying Sum of Square Difference (SSD) tracking to the reference and second images.
3. The method of claim 1 , wherein the 3D object is part of a turbine moving in an atmosphere with a temperature greater than 400 degrees F.
4. The method of claim 1 , wherein the predetermined pattern is a checkerboard pattern.
5. The method of claim 1 , wherein the standard format image shape is a square.
6. The method of claim 1 , wherein the patch covers about 3600 pixels.
7. The method of claim 1 , wherein the movement of the 3D object includes a vibrational movement of a frequency greater than 100 Hz.
8. The method of claim 1 , wherein the 3D object experiences a circumferential movement about an axis and a translational movement along the axis.
9. The method of claim 1 , wherein the plurality of images is generated with an infra-red image sensor.
10. The method of claim 1 , wherein the warping is determined by a 2.times.2 projective transformation of each image element in a sub-patch to an image element in a corrected image.
11. A system to track a 3D object in a plurality of images, comprising:
a memory enabled to store data including instructions;
a processor enabled to execute instructions to perform the steps:
identifying a patch containing at least part of a predetermined pattern on the 3D object in a reference image in the plurality of images;
determining a plurality of sub-patches in the patch;
for each of the plurality of sub-patches in the patch, warping a captured part of the predetermined pattern to a standard format image shape;
determining an image area inside the patch in a second image;
warping image data of the second image inside the patch; and
determining a movement of the 3D object from the reference image and the second image.
12. The system of claim 11 , wherein the movement is determined by applying Sum of Square Difference (SSD) tracking to the reference and second images.
13. The system of claim 11 , wherein the 3D object is part of a turbine moving in an atmosphere with a temperature greater than 400 degrees F.
14. The system of claim 11 , wherein the predetermined pattern is a checkerboard pattern.
15. The system of claim 11 , wherein the standard format image shape is a square.
16. The system of claim 11 , wherein the patch covers about 3600 pixels.
17. The system of claim 11 , wherein the movement of the 3D object includes a vibrational movement of a frequency greater than 100 Hz.
18. The system of claim 11 , wherein the 3D object experiences a circumferential movement about an axis and a translational movement along the axis.
19. The system of claim 11 , wherein the plurality of images is generated with an infra-red image sensor.
20. The system of claim 11 , wherein the warping is determined by a 2.times.2 projective transformation of each image element in a sub-patch to an image element in a corrected image.