Principle of Digital Image Correlation

Dig­i­tal Image Cor­re­la­tion (often referred to as “DIC”) is an easy to use proven opti­cal method to mea­sure defor­ma­tion on an object sur­face. The method tracks the gray val­ue pat­tern in small neigh­bor­hoods called sub­sets (indi­cat­ed in red in the fig­ure below) dur­ing defor­ma­tion. Dig­i­tal Image Cor­re­la­tion has been proven over and over to be accu­rate when com­pared to valid FEA mod­els. The com­mer­cial­ly avail­able VIC-2D and VIC-3D sys­tems from Cor­re­lat­ed Solu­tions both uti­lize this advanced opti­cal mea­sure­ment technology.


Digital Image Correlation Overview

Below are the rea­sons why its ver­sa­til­i­ty, robust­ness, and ease of use make it the only choice when it comes to dig­i­tal image correlation.

DIC - Principle of Digital Image Correlation

Two-dimensional Example

In the two pic­tures below you can see a speck­le pat­tern on an alu­minum sam­ple with two off­set semi-cir­cu­lar cut-outs. The two pic­tures were tak­en from an ani­ma­tion with the left image tak­en from the begin­ning and the right pic­ture tak­en from the end of the ani­ma­tion. Since the defor­ma­tion is pre­dom­i­nant­ly in-plane, a sin­gle cam­era can be used to mea­sure the deformation.


Small Defor­ma­tion


Large Defor­ma­tion

The pic­tures below show the hor­i­zon­tal strain mea­sured by two-dimen­sion­al image cor­re­la­tion for the pic­tures shown above.

VIC2D-2 VIC2D-2a

Three-dimensional Example

These two speck­le images below were tak­en simul­ta­ne­ous­ly with the left and right cam­era of a stereo-sys­tem. The sam­ple itself is a piece of glass with the com­pa­ny logo stick­er adhered to the sur­face.  The speck­le pat­tern was applied using stan­dard off-the-shelf flat white and black spray paint.  Can you make out the shape?

Left View
Right View

In the plot below the shape of the logo stick­er mea­sured with the VIC-3D Sys­tem is shown. The thick­ness of the logo stick­er is approx­i­mate­ly 0.003″ or 0.070mm.

For more info­ma­tion have a look at our DIC prod­ucts or con­tact us via or +49 561 — 739798–0