I am actually working with two different sand with two different material properties, because just the normal sand images was not able to track the deformation using geoPIV, I am trying to add different material to get the enough texture difference and pixel intensity. Because of my transparent perspex is in the front side of my model, I have to pour sand mixture of certain width from certain height and it needs to homogeneously presented for good results and good presentation.

I attached some of the images of my research, can you please have a look and suggest me any suitable ideas for the experimental setup .