Determining imperfections in an imaging camera for determining the orientation of objects in space
A method and system determines object orientation using a light source to create a shadow line extending from the light source. A camera captures an image including the shadow line on an object surface. An orientation module determines the surface orientation from the shadow line. In some examples a transparency imperfection in a window through which a camera receives light can be detected and a message sent to a user as to the presence of a light-blocking or light-distorting substance or particle. A system can control illumination while imaging an object in space using a light source mounted to a support structure so a camera captures an image of the illuminated object. Direct illumination of the camera by light from the light source can be prevented such as by blocking the light or using a light-transmissive window adjacent the camera to reject light transmitted directly from the light source.
1. A method for determining a transparency imperfection of an imaging camera for determining orientations of objects in space, the method comprising:
operating a light source partially blocked by an at least partially opaque structure portion that is formed to protrude from a surface of a structure housing the light source and protruding substantially in a direction of the object to create a shadow line extending from the light source;
capturing, using a camera, a first image comprising an object intersecting the shadow line;
capturing, a second image comprising the object taken with the camera while the light source is not projecting light; and
analyzing the first image compared to the second image to detect a transparency imperfection of a transparent window through which the camera receives light.
2. The method of claim 1 , wherein detecting a transparency imperfection further comprises detecting a light-blocking or light-distorting substance or particle on a transparent window through which the camera receives light.
3. The method of claim 2 , further comprising sending a message to a user informing the user of a presence of said light-blocking or light-distorting substance or particle.
4. The method of claim 1 , wherein detecting the transparency imperfection comprises searching for an illuminated portion of the first image that is not illuminated in the second image.
5. The method of claim 1 , wherein the shadow line is created by blocking a portion of light emitted by the light source with the at least partially opaque structure portion, an orientation of the at least partially opaque structure portion being based also on a configuration and position of the structure housing the light source relative to the light source.
6. The method of claim 1 , wherein the light source is a light-emitting diode.
7. The method of claim 1 , wherein the at least partially opaque structure portion includes a collar that encompasses the light source.
8. The method of claim 7 , wherein the at least partially opaque structure portion comprises a protrusion acting to at least partially block light from the light source.
9. The method of claim 7 , wherein the at least partially opaque structure portion comprises a recess in a wall acting as the structure housing the light source.
10. The method of claim 1 , wherein analyzing an image comprises analyzing rows of the image to detect increases or decreases in luminescence therein.
11. The method of claim 1 , further comprising preventing direct illumination of the camera by light from the light source.
12. The method of claim 11 , wherein preventing direct illumination comprises creating, during light source operation, an un-illuminated region to one side of the shadow line, the camera being located within the un-illuminated region.
13. The method of claim 11 , wherein preventing direct illumination comprises shielding the camera with a window configured to reject light transmitted directly from the light source to the window.
14. The method of claim 1 , wherein the shadow line is not a straight line.
15. The method of claim 1 , further comprising determining an orientation of an object based at least in part on a position of the shadow line on the object as imaged.
16. The method of claim 15 , wherein analyzing an image further comprises:
determining a first position of a shadow line;
determining a second position of the shadow line;
comparing the first position and the second position of the shadow line to detect a difference in shadow line position; and
determining that the orientation of the object has changed based at least in part upon detecting the difference between the first position of the shadow line and the second position of the shadow line.
17. The method of claim 16 , further comprising moving the shadow line by moving the light source or the at least partially opaque structure portion.
18. A system comprising:
a light source for emitting light;
a light blocking structure positioned to protrude from a surface of a structure housing the light source and protruding within a path of light emanating from the light source housed in a direction of an object so that a portion of the light emitted from the light source is blocked thereby creating a shadow line extending from the light source;
a camera for capturing a first image comprising the shadow line on a surface of an object and capturing, a second image comprising the object taken with the camera while the light source is not projecting light; and
an orientation module including at least one processor coupled to a memory storing instructions that when executed by the at least one processor analyze the first image compared to the second image to detect a transparency imperfection of a transparent window through which the camera receives light.
19. The system of claim 18 , wherein the light blocking structure includes a collar that encompasses the light source.
20. A non-transitory computer readable medium storing instructions for determining a transparency imperfection of an imaging camera for determining orientations of objects in space, which instructions when executed by one or more processors perform a method comprising:
operating a light source partially blocked by an at least partially opaque structure portion that is formed to protrude from a surface of a structure housing the light source and protruding substantially in a direction of the object to create a shadow line extending from the light source;
capturing, using a camera, a first image comprising an object intersecting the shadow line;
capturing, a second image comprising the object taken with the camera while the light source is not projecting light; and
analyzing the first image compared to the second image to detect a transparency imperfection of a transparent window through which the camera receives light.