In our last article, “How Do I Print Wood", we learned how to 3D print a texture in full-color using the Agilus30 White material on the Stratasys J750. We discussed how to use new SOLIDWORKS 2019 features to create physical 3D displacement models using a 2D bump mapping pattern and then apply the color texture to the model in Adobe Photoshop CC.
In this article, I’m going to show you another method to accomplish nearly the same end product, this time using a stone texture and only Adobe Photoshop CC. What’s more, we’ll go into how 3D displacement using bump maps in Photoshop works, showing you a quick and easy method to manually alter those bump maps to make smoother or coarser physical textures.
What is a Bump Map?
To create a 3D textured model for printing using just Photoshop, we’re going to need to either have a bump map that matches a full-color 2D image or create a bump map image using a normal 2D full-color file. If you have access to a matching set of images, great! This will contain all the data that you need to go from 2D, to 3D, to print. If not, don’t worry; all we need to do is take our full-color image, desaturate it, and adjust the levels, contrast and brightness so that you have nicely toned white regions (high points), black regions (low points) and grey in between which will be the curved surfaces attaching those two regions on our final 3D model.
This step can be done either before you start working on your project, or during the project, once we get to the bump mapping phase. It’s usually safer to do beforehand so you don’t accidentally save over your initial color file, as we’ll need both to make this work, but if you're cautious about saving your work properly we shouldn't run into any issues.
Turning a 2D Image Into a 3D Object
How do we use Photoshop to turn a 2D image into a 3D Object? All we need to do is choose the 3D tab from the layers pane, choose 3D extrusion, click create and choose an appropriate extrusion depth from the following properties tab. Make sure that when you choose an extrusion depth you keep in mind the size of your current image (in my case, 41.67” x 27.78”), and pick a depth that will scale properly when you import it into the printer and shrink it. With my current X/Y dimensions I've set the depth to 2 inches of depth in order to hit roughly 0.25" as my end thickness after scaling.
Now that we have a 3D extruded part, it’s time to add our bump map texture. To do this, we’ll again click on the 3D tab, but this time we’ll click on the top background layer from this menu, and then click on the folder icon in the properties window next to the bump field. While we can generate a bump map from the diffused layer, this is going to use our original full-color image to create the bump mapping, which isn’t ideal as it won’t have the strong peaks and valleys that black and white bump maps would have. Instead, we’ll choose either to load the texture you’ve already saved that is a desaturated and edited bump map file, or click new texture if you are going to pull the original image in and edit in the bump map layer.
If choosing the new texture option, first click File -> Place Embedded and navigate to the same full-color image that you originally started with. It will place that image into the bump map layer, but inside of this layer it will not overwrite the original full-color file, as the bump map layer is automatically going to save as a different file name in the same folder. Then, go to Image -> Adjustments -> Desaturate, followed by using the same adjustments options to toggle the levels, brightness and contrast until you have a bump map that has strong white and black areas. Once completed, close out that image and save when prompted, and it will automatically update on the 3D model.
Controlling the Displacement Depth
Now that we have bump maps in place along with a matching color image on our 3D model, we can open the 3D -> 3D print settings menu and adjust our properties to control just how large our cuts in and extrusions out will be on the final 3D model. Make sure that you have the J750 chosen, and then in the surface detail group, you can adjust the Min and Max values of physical displacement. Min is typically negative, which means that it will be allowed to go x units of measure below the surface of the flat plane, and the Max is typically positive as this allows the high values to be extruded off the flat plane by x amount. Don’t go too wild here, as extreme values get out of control quickly and create unbelievably absurd textures that look like blades of grass in a yard, but small deviations will produce very accurate simulations of raised and depressed areas of rock face.
After choosing your values, click 3D -> 3D print, and Photoshop will then do all of the processing required to turn your object into a VRML, ready to pull into GrabCAD Print.
Augmenting the Bump Maps to Alter Smoothness
One other neat thing that we can do, going back to the bump map step creation, is to artificially augment areas of the bump map using the brush tool set for black or white at a low hardness so the edges have a soft transition to the untouched regions. Doing so in our example, we’ve created three corners that will be lower than all other points on the model, and one corner and the center that will be higher, with a transition range in the middle. Additionally, as long as the painting is done in a new layer of the bump map, you can adjust the translucency of this layer, which will still lower or raise the impacted regions, but will also allow much of the original detail to come through.
With a bit of minor additional tweaking to the 2D bump map image you can take your texture from one look to a completely different look in a matter of minutes! Using the Stratasys J750 loaded with the VeroVivid Color Family and Agilus30 White, along with Adobe Photoshop CC, you can easily create full textured three-dimensional models that both feel and look incredibly true to life. This is a fascinating application for this incredible technology, and it empowers the user to create virtually anything that they can think of!
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