3D Sensors with 2D

There are applications where a 3D profile of an object is required for some processing and a 2D colour image is required for other processing required on the same object. 

The principle of triangulation where single / multiple laser points / lines provide a detailed 3D profile of an object being measured.  This is often presented in a mesh of 3D data points as shown in th '3D Profile Map'. 

There are also a broad range of applications in inspection that use a 2D image (a picture of the surface), which is analyzed to determine a variety of information such as surface quality (detecting defects which are a different contrast or colour) or surface features, such as holes.  In applications which require detection of both 3D geometry and 2D surface information, the traditional approach has been to use two sensors, each with their own package, mounting, cabling and support electronics, which is both expensive and complex to integrate and operate.  There is also the complexity of aligning both sensors in the field as well as the data synchronization to ensure they are both measuring the same object at the same time.  This can be time consuming and challenging.

An example, as demonstrated in the images is the manufacturing of lumber.  3D profiling is required to measure dimensions and to place saw lines appropriately, whereas, the surface colour images will show where defects (knots, stain, grain) greatly effect the value of the resulting decisions.  In some cases adjusting the location of a sawline makes no difference to the size of the lumber, yet cutting out a series of knots can double the value of the resulting lumber.

Another example is the web scanning of patterned print material.  Typically the images are continuously scanning to ensure the print registration is correct.  In some situation, the material may be dimensionally deformed with a dip or bulge in the material that would not be easily identified using a 2D camera looking at the print surface.  Adding a 3D profile camera to work together with the 2D colour camera would immediately detect this defect.  This is the combination of two well known and proven technologies that each perform their respective tasks extremely well without trying to force one technology to do two jobs poorly.

LMI has developed a solution which combines both 2D and 3D data acquisition in a single sensor package which greatly simplifies the work of the user. These sensors house both laser illumination for 3D geometry measurement and LED surface illumination for 2D colour surface imaging.  The images are further processed in the sensor to correctly map the 2D colour image onto the 3D profile.  This could not easily be done with individual cameras in a real time system.