CN114295076B - Measuring method for solving shadow measuring problem of tiny object based on structured light - Google Patents

Abstract

The invention discloses a measuring method for solving the problem of shadow measurement of a tiny object based on structured light, which comprises the steps of firstly, using two standard projectors with telecentric lenses to respectively project blue monochromatic stripes and red monochromatic stripes onto the object to be measured from left and right directions at the same time; then capturing superimposed red and blue stripes with measured object information by using a color camera, and carrying out three-way separation on the acquired picture to obtain information of a red channel and a blue channel; and then, obtaining three-dimensional point cloud data of the separated red and blue channel information through a phase shift method and a multi-frequency heterodyne method, generating information required by mask screening, and finally fusing the obtained two point clouds of the red and blue channels so as to solve the problem of inherent shadow in the measurement of the tiny object. The method for simultaneously measuring the three-dimensional micro object by utilizing the red and blue channels can solve the problem of shadow which is difficult to avoid during the measurement of the three-dimensional micro object, and has great value in the field of high-precision and high-dynamic three-dimensional micro object measurement.

Description

A measurement method to solve the shadow problem of small object measurement based on structured light

Technical field

The invention relates to a method for solving the shadow of an optical three-dimensional measurement system, which belongs to the field of photoelectric detection technology, and specifically relates to a measurement method that solves the problem of shadow measurement of small objects based on structured light.

Background technique

The three-dimensional reconstruction method based on structured light systems is becoming increasingly mature. Compared with traditional image-based photogrammetry or multi-view geometry methods, it is simpler, faster, and more reliable. It is widely used in high-tech industries (such as microelectronic chip industry, consumer electronics It has been widely used in the connector industry, optoelectronic semiconductor industry, industrial circuit board industry, small medical equipment, jewelry cutting industry, etc.), urban building modeling, and reconstruction of small cultural relics. Aiming at the problems of precise measurement of small objects, measurement shadows of complex shapes and measurement dead spots in structured light projection measurement technology, the present invention expands the imaging range by adding an auxiliary light source based on the traditional monocular vision measurement system. A new dual-projection structured light system was established to solve the shadow problem faced by traditional structured light measurement systems. Based on the existing single projector and single camera, another projector is added to solve the shadow problem. One projector projects a monochromatic blue stripe, and the other projector projects a monochromatic red stripe. Two projectors project stripes onto the object at the same time. After collecting the images, three channels are separated for point cloud fusion to solve the occlusion and shadow problems of the system's optical structure based on the triangulation method.

Contents of the invention

The purpose of the present invention is to propose a measurement method that solves the shadow problem of measuring small objects based on structured light. The present invention uses a method of simultaneous measurement of red and blue channels to solve the shadow problem that is difficult to avoid when measuring three-dimensional small objects, and compared with Compared with the traditional dual-projector system, this method has higher measurement efficiency and measurement speed, and is of great value in the field of high-precision, high-dynamic three-dimensional micro-object measurement;

In order to achieve the above object, the present invention adopts the following technical solution: a measurement method to solve the problem of shadow measurement of small objects based on structured light. The method includes the following steps:

Step 1. Build the system: The system includes a computer, two DLP projectors equipped with telecentric lenses, a CCD color camera equipped with telecentric lenses, a reference plane and a bracket. The DLP projectors and CCD color cameras are connected through data lines respectively. Computer, the measured object is placed on the reference plane. The computer contains an image acquisition card, projection software and measurement software. The CCD color camera equipped with a telecentric lens is fixed on a bracket that can move vertically up and down, and two equipped with DLP projectors with telecentric lenses are placed on both sides of the object being measured, and then the entire system is calibrated;

Step 2. Collect pictures and separate information: Two DLP projectors simultaneously project red horizontal stripes and blue horizontal stripes onto the object being measured, and then use a CCD color camera to collect pictures; conduct red, green, and blue channels on the collected pictures. By separation, the object information of three channels can be obtained, retaining the information of the red and blue channels, and discarding the information of the green channel;

Step 3. Obtain the point cloud: Obtain the three-dimensional point cloud data of the red and blue channel information obtained in step 2 through the phase shift method and the multi-frequency heterodyne method;

Step 4. Point cloud fusion: Fusion of the red and blue channel three-dimensional point clouds obtained in step 3, by retrieving the gray value of the separated red channel image, marking pixels with a gray value greater than or equal to 255 and setting them to 0 , set other areas to 1, generate a mask, use this mask to process the obtained three-dimensional point cloud of red and blue channels, retain the intact area without shadow, fuse the two point clouds, and obtain a three-dimensional object point cloud without shadow Contour, thereby obtaining the complete three-dimensional shape of the measured object.

A measurement method to solve the problem of shadow measurement of small objects based on structured light, including the following steps:

Step 1. Build the system: The system includes a computer, two DLP projectors equipped with telecentric lenses, a CCD color camera equipped with telecentric lenses, a reference plane and a bracket. The DLP projectors and CCD color cameras are connected through data lines respectively. Computer, the measured object is placed on the reference plane. The computer contains an image acquisition card, projection software and measurement software. The CCD color camera equipped with a telecentric lens is fixed on a bracket that can move vertically up and down, and two equipped with DLP projectors with telecentric lenses are placed on both sides of the object being measured, and then the entire system is calibrated;

Step 2. Collect pictures and separate information: Two DLP projectors simultaneously project red horizontal stripes and blue horizontal stripes onto the object being measured, and then use a CCD color camera to collect pictures; conduct red, green, and blue channels on the collected pictures. By separation, the object information of three channels can be obtained, retaining the information of the red and blue channels, and discarding the information of the green channel;

Step 3. Obtain the point cloud: Obtain the three-dimensional point cloud data of the red and blue channel information obtained in step 2 through the phase shift method and the multi-frequency heterodyne method;

Step 4. Point cloud fusion: Fusion of the red and blue channel three-dimensional point clouds obtained in step 3, by retrieving the gray value of the separated red channel image, marking pixels with a gray value greater than or equal to 255 and setting them to 0 , set other areas to 1, generate a mask, use this mask to process the obtained three-dimensional point cloud of red and blue channels, retain the intact area without shadow, fuse the two point clouds, and obtain a three-dimensional object point cloud without shadow Contour, thereby obtaining the complete three-dimensional shape of the measured object.

The beneficial effects of the present invention are:

Compared with the traditional dual-projector measurement system, the present invention can reduce the number of pictures by half, improve measurement efficiency and measurement speed; solve the problem of difficult grating separation in the traditional dual-projector system; and solve the problem of small object measurement based on structured light. inherent shadowing issues.

Description of the drawings

Figure 1 is a schematic diagram of the measurement system of the present invention;

Figure 2 is a picture collected by the color CCD camera of the system of the present invention;

Figure 3 is a mask image generated by the present invention based on the collected pictures.

Detailed ways

It is easy to understand that according to the technical solutions of the present invention, those of ordinary skill in the art can imagine various implementations of the present invention without changing the essential spirit of the present invention. Therefore, the following specific embodiments and drawings are only illustrative descriptions of the technical solutions of the present invention, and should not be regarded as the entirety of the present invention or as limitations or limitations to the technical solutions of the present invention. Examples of the present invention will be described in further detail below with reference to the accompanying drawings. However, this example is not intended to limit the present invention. Any similar structures and similar changes using the present invention should be included in the protection scope of the present invention.

A measurement method of the present invention that solves the problem of shadow measurement of small objects based on structured light. The steps are as follows:

1. Build the system: As shown in Figure 1, the system includes a computer 1, a DLP projector equipped with a telecentric lens 2 and a DLP projector equipped with a telecentric lens 4, a CCD color camera equipped with a telecentric lens 3. The reference plane 6 and the bracket, the DLP projector 2, the DLP projector 4 and the CCD color camera 3 are connected to the computer 1 through data cables respectively. The measured object 5 is placed on the reference plane 6. The computer 1 contains an image capture card, projection software and Measurement software, fix the CCD color camera 3 equipped with a telecentric lens on a bracket that can move vertically up and down, and place two DPL projectors equipped with telecentric lenses on both sides of the measured object 5, and then measure the The entire system is calibrated;

2. Collect pictures and separate information: Two DLP projectors simultaneously project red horizontal stripes and blue horizontal stripes onto the object being measured, and then use a CCD color camera to collect pictures; separate the collected pictures into three channels of red, green and blue. , the object information of three channels can be obtained, the information of the red and blue channels is retained, and the information of the green channel is discarded; let the picture captured by the color camera be I (x, y), and I _r (x, y) is the picture captured by the camera. The red channel information of I _g (x, y) is the red channel information of the picture captured by the camera, and I _b (x, y) is the blue channel information of the picture captured by the camera. The relationship between them can be expressed by Equation (1):

I(x,y)＝I _r (x,y)+I _g (x,y)+I _b (x,y) (1)

3. Obtain the three-dimensional point cloud: obtain the three-dimensional point cloud of the obtained red and blue channel information through the phase shift method and the multi-frequency heterodyne method;

4. Three-dimensional point cloud fusion: fuse the obtained three-dimensional point clouds of red and blue channels. By retrieving the grayscale value of the separated red channel image, marking pixels with a grayscale value greater than or equal to 255 and setting them to 0, and setting other areas to 1, a mask is generated. In this method, the grayscale values of two monochromatic images I _r (x, y) and I _b (x, y), red and blue, are judged to mark the shadow area of each channel. The masks corresponding to the saturated areas of the B channel and R channel are obtained from equations (2) and (3):

As shown in Figure 2, the picture with the object under test is collected by the camera. Figure 3 is a mask generated based on the gray value filtering in Figure 2. Use the generated mask to process the obtained three-dimensional point cloud of red and blue channels to retain the intact area without shadows. The two point clouds are fused to obtain a shadow-free three-dimensional object point cloud outline, thereby obtaining a complete three-dimensional view of the measured object. Appearance.

It is not limited to this, and any changes or substitutions without creative efforts should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.

Claims (1)

1. A measurement method to solve the problem of shadow measurement of small objects based on structured light, which is characterized by including the following steps: Step 1. Build the system: The system includes a computer, two DLP projectors equipped with telecentric lenses, a CCD color camera equipped with telecentric lenses, a reference plane and a bracket. The DLP projectors and CCD color cameras are connected through data lines respectively. Computer, the measured object is placed on the reference plane. The computer contains an image acquisition card, projection software and measurement software. The CCD color camera equipped with a telecentric lens is fixed on a bracket that can move vertically up and down, and two equipped with DLP projectors with telecentric lenses are placed on both sides of the object being measured, and then the entire system is calibrated; Step 2. Collect pictures and separate information: Two DLP projectors simultaneously project red horizontal stripes and blue horizontal stripes onto the object being measured, and then use a CCD color camera to collect pictures; conduct red, green, and blue channels on the collected pictures. By separation, the object information of three channels can be obtained, retaining the information of the red and blue channels, and discarding the information of the green channel; Step 3. Obtain the point cloud: Obtain the three-dimensional point cloud data of the red and blue channel information obtained in step 2 through the phase shift method and the multi-frequency heterodyne method; Step 4. Point cloud fusion: Fusion of the red and blue channel three-dimensional point clouds obtained in step 3, by retrieving the gray value of the separated red channel image, marking pixels with a gray value greater than or equal to 255 and setting them to 0 , other areas are set to 1, a mask is generated, and the grayscale values of the red and blue monochrome images I _r (x, y) and I _b (x, y) are judged to mark the shadow area of each channel; the B channel and The mask corresponding to the saturated area of the R channel is obtained by equation (1) and equation (2): The mask is used to process the obtained three-dimensional point cloud of the red and blue channels to retain the intact area without shadows. The two point clouds are fused to obtain a shadow-free three-dimensional object point cloud outline, thereby obtaining the complete three-dimensional shape of the measured object. appearance.