Method for automatic focus and PTZ camera

Patent metadata

Field	Value
Publication number	US-10652452-B2
Application number	US-201716066105-A
Country	US
Kind code	B2
Filing date	Nov 1, 2017
Priority date	Nov 15, 2016
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

Embodiments of the present application provide an automatic focusing method and a PTZ camera. The method is applicable to the PTZ camera and comprises: calculating a current target object distance from a lens of the PTZ camera to a monitored target monitoring plane based on a pre-established spatial object distance parameter; wherein, the spatial object distance parameter contains a spatial plane equation of a reference monitoring plane; the reference monitoring plane is an equivalent plane of the target monitoring plane; searching in a preset relation table based on the current target object distance, a current magnification of the PTZ camera, determining a position information corresponding to a focus motor of the PTZ camera, the preset relation table including the relationship of the object distance, the magnification and the position information of the focus motor, and driving the focus motor to a position corresponding to the determined position information. Embodiments of the present application are applied to realize fast automatic focusing of the PTZ camera.

First claim

The invention claimed is:

1. An automatic focusing method applicable to a PTZ camera, the method comprises:
calculating a current target object distance from a lens of the PTZ camera to a monitored target monitoring plane based on a pre-established spatial object distance parameter; wherein the spatial object distance parameter contains a spatial plane equation of a reference monitoring plane; the reference monitoring plane is used as an equivalent plane of the target monitoring plane;
searching in a preset relation table based on the current target object distance, a current magnification of the PTZ camera, determining a position information corresponding to a focus motor of the PTZ camera and driving the focus motor to a position corresponding to the position information;
wherein, the preset relation table comprises the relationship between the target object distance, the magnification and the position information of the focus motor;
wherein calculating a current target object distance from the lens of the PTZ camera to a monitored target monitoring plane based on a pre-established spatial object distance parameter, comprises:
obtaining a spatial plane equation contained in the pre-established spatial object distance parameter;
determining a spatial rectangular coordinate system where the spatial plane equation is located;
determining a first angle formed between the lens of the PTZ camera and a Z-axis of the spatial rectangular coordinate system, and a second angle formed between the lens and an X-axis of the spatial rectangular coordinate system;
calculating a center point distance from the origin of the spatial rectangular coordinate system to the center point of the reference monitoring plane based on the first angle, the second angle and the spatial plane equation, and taking the center point distance as the current target object distance from the lens of the PTZ camera to the monitored target monitoring plane;
wherein the center point is the intersection of a line where a target unit vector is located and the reference monitoring plane; the target unit vector is a unit vector that is originated from the origin and determined based on the first angle and the second angle; the origin is the intersection of rotation axes of the PTZ camera; the rotation axes of the PTZ camera comprise a rotation axis about which the PTZ camera rotates in a horizontal direction and a rotation axis about which the PTZ camera rotates in a vertical direction.

2. The method of claim 1 , wherein establishing a spatial object distance parameter comprises:
determining the reference monitoring plane of the PTZ camera;
determining spatial coordinates of at least three target points in the reference monitoring plane;
calculating the spatial plane equation of the reference monitoring plane based on spatial coordinates of each target point to establish the spatial object distance parameter.

3. The method of claim 2 , wherein determining spatial coordinates of any target point of the three target points comprises:
obtaining a distance from any target point in a spatial rectangular coordinate system to the lens of the PTZ camera, wherein an origin of the spatial rectangular coordinate system is an intersection of rotation axes of the PTZ camera; the rotation axes of the PTZ camera comprise a rotation axis about which the PTZ camera rotates in a horizontal direction and a rotation axis about which the PTZ camera rotates in a vertical direction;
obtaining a position information of the lens of the PTZ camera in the spatial rectangular coordinate system;
calculating the spatial coordinates of any target point based on the distance and the position information of the lens of the PTZ camera in the spatial rectangular coordinate system.

4. The method of claim 3 , wherein obtaining a distance from any target point in a spatial rectangular coordinate system to the lens of the PTZ camera comprises:
calculating, under a preset magnification, position information of the focus motor when focusing on any target point using a contrast automatic focusing algorithm;
calculating the distance from any target point to the lens of the PTZ camera based on the preset magnification, the position information calculated using the contrast automatic focusing algorithm and the preset relation table.

5. The method of claim 3 , wherein, the spatial rectangular coordinate system comprises an X-axis, a Y-axis, and a Z-axis;
the position information of the lens of the PTZ camera in the spatial rectangular coordinate system comprises:
a first angle formed between the lens of the PTZ camera and the Z-axis of the spatial rectangular coordinate system, and a second angle formed between the lens of the PTZ camera and the X-axis of the spatial rectangular coordinate system.

6. The method of claim 1 , wherein calculating a current target object distance from the lens of the PTZ camera to a monitored target monitoring plane based on a pre-established spatial object distance parameter comprises:
obtaining a spatial plane equation contained in the pre-established spatial object distance parameter;
determining a spatial rectangular coordinate system where the spatial plane equation is located;
calculating a vertical distance from the origin of the spatial rectangular coordinate system to the reference monitoring plane based on the spatial coordinates of the origin and the spatial plane equation, and taking the vertical distance as the current target object distance from the lens of the PTZ camera to the monitored target monitoring plane;
wherein the origin is the intersection of rotation axes of the PTZ camera; the rotation axes of the PTZ camera comprise a rotation axis about which the PTZ camera rotates in a horizontal direction and a rotation axis about which the PTZ camera rotates in a vertical direction.

7. A non-transitory storage medium, wherein the storage medium is configured for storing a executable program code, the executable program code is configured for implementing the automatic focusing method of claim 1 when being executed.

8. A PTZ camera, comprising:
an establishing module, configured for establishing a spatial object distance parameter;
a calculating module, configured for calculating a current target object distance from a lens of the PTZ camera to a monitored target monitoring plane based on the spatial object distance parameter pre-established by the establishing module; wherein the spatial object distance parameter contains a spatial plane equation of a reference monitoring plane; the reference monitoring plane is an equivalent plane of the target monitoring plane;
a searching module, configured for searching in a preset relation table based on the current target object distance, a current magnification of the PTZ camera, and determining a position information corresponding to a focus motor of the PTZ camera;
a driving module, configured for driving the focus motor to a position corresponding to the position information;
wherein the preset relation table comprises the relationship between the target object distance, the magnification and the position information of the focus motor;
wherein the calculating module comprises:
a second obtaining sub-module, configured for obtaining a spatial plane equation contained in a pre-established spatial object distance parameter;
a fourth determining sub-module, configured for determining a spatial rectangular coordinate system where the spatial plane equation is located;
a fifth determining sub-module, configured for determining a first angle formed between the lens of the PTZ camera and a Z-axis of the spatial rectangular coordinate system and a second angle formed between the lens and an X-axis of the spatial rectangular coordin

Assignees

• Hangzhou Hikvision Digital Tec

Inventors

• Gong Qi
• Ma Weimin
• You can
• Xu Peng

Classifications

• G03B13/36

  Autofocus systems · CPC title

• G02B7/30

  using parallactic triangle with a base line · CPC title

• H04N5/23296

  Electricity · mapped topic

• H04N5/23299

  Electricity · mapped topic

• H04N5/232123 Primary

  Electricity · mapped topic