A launch monitor having a camera can be used to measure a trajectory parameter of a ball. In one example, a method can include changing a mode of the camera from a low-speed mode to a high-speed mode. The camera can include an image sensor array having a plurality of pixels. The camera can generate a video frame using more pixels in the low-speed mode than in the high-speed mode. A first video frame can be received, the video frame comprising values captured during the high-speed mode from a first subset of the plurality of pixels. A second video frame can be received, the video frame comprising values captured during the high-speed mode from a second subset of the plurality of pixels. The trajectory parameter of the ball can be calculated using the first video frame and the second video frame.
1. A method for determining a trajectory parameter of a golf ball, comprising:
using an accelerometer to detect that an image sensor is stationary;
in response to detecting that the image sensor is stationary, changing a mode of the image sensor to a high-speed mode, wherein the image sensor in high-speed mode has a frame rate that is faster than when the image sensor is not in high-speed mode;
capturing a first video frame of the golf ball using a first subset of pixels of the image sensor when in the high-speed mode;
capturing a second video frame of the golf ball using a second subset of pixels of the image sensor when in the high-speed mode; and
calculating the trajectory parameter of the golf ball using the first video frame and the second video frame.
2. The method of claim 1 , wherein the trajectory parameter of the golf ball is spin, and a logo of the golf ball is used as a fiduciary marker to calculate the spin.
3. The method of claim 1 , wherein the first subset of pixels of the image sensor include only even rows of the image sensor and the second subset of pixels of the image sensor include only odd rows of the image sensor.
4. The method of claim 1 , wherein the first subset of pixels and the second subset pixels of the image sensor are the same.
5. The method of claim 1 , wherein the trajectory parameter of the golf ball is launch angle.
6. The method of claim 1 , wherein the trajectory parameter of the golf ball is speed.
7. The method of claim 1 , wherein the mode of the image sensor is changed to the high-speed mode when the golf ball is detected in a third video frame captured from the image sensor.
8. The method of claim 1 , wherein the mode of the image sensor is changed to the high-speed mode in response to a launch monitor application being started.
9. A non-transitory computer-readable storage having instructions thereon for executing a method of calculating a trajectory parameter of a ball, the method comprising:
detecting that a camera is stationary;
after detecting that the camera is stationary, changing a mode of the camera from a low-speed mode to a high-speed mode, the camera comprising an image sensor array having a plurality of pixels, and wherein the camera generates a video frame using more pixels in the low-speed mode than in the high-speed mode so that the high-speed mode has a higher frame rate than in the low-speed mode;
receiving a first video frame comprising values captured during the high-speed mode from a first subset of the plurality of pixels;
receiving a second video frame comprising values captured during the high-speed mode from a second subset of the plurality of pixels;
calculating the trajectory parameter of the ball using at least one of the first video frame and the second video frame.
10. The computer-readable storage medium of claim 9 , wherein the camera captures a sub-array of the plurality of pixels during the high-speed mode.
11. The computer-readable storage medium of claim 9 , wherein the camera uses interlaced scanning of the image sensor array during the high-speed mode and progressive scanning of the image sensor array during the low-speed mode.
12. The computer-readable storage medium of claim 9 , wherein the camera captures a sub-array of the plurality of pixels using interlaced scanning of the image sensor array during the high-speed mode.
13. The computer-readable storage medium of claim 9 , wherein the trajectory parameter of the ball is spin, and a logo of the ball is used as a fiduciary marker when calculating the spin.
14. The computer-readable storage medium of claim 9 , wherein the trajectory parameter of the ball is calculated using an extent of motion blur within the first video frame.
15. The computer-readable storage medium of claim 9 , wherein the trajectory parameter of the ball is calculated based on a relative motion of the ball between the first video frame and the second video frame.
16. A mobile device for monitoring a golf ball, comprising:
a processor;
an accelerometer;
a camera comprising an image sensor including a plurality of pixels and a plurality of scan patterns for capturing a video frame, the plurality of scan patterns including a high-speed scan pattern and a low-speed scan pattern; and
a computer-readable storage medium including instructions that upon execution cause the processor to:
use an output of the accelerometer to detect whether the mobile device is stationary;
detect the golf ball in a field of view of the camera;
when the mobile device is detected to be stationary and the golf ball is detected in the field of view of the camera, use the high-speed scan pattern so that fewer pixels are scanned per video frame than when the low-speed scan pattern is used; and
calculate a motion parameter of the golf ball using one or more video frames captured by the image sensor.
17. The mobile device of claim 16 , wherein the high-speed scan pattern is an interlaced scan pattern and the low-speed scan pattern is a progressive scan pattern.
18. The mobile device of claim 16 , wherein the high-speed scan pattern scans a sub-array of plurality of the pixels and the low-speed scan pattern scans all of the plurality of pixels.
19. The mobile device of claim 16 , wherein the motion parameter is a magnitude and a direction of a spin axis of the golf ball, and a logo of the golf ball is used as a fiduciary marker.
20. The mobile device of claim 16 , wherein the motion parameter of the golf ball is calculated using an extent of motion blur within one video frame.