Using Reference Images in 3D Modeling - Tutorial
Updated: Sep 21, 2020
This is the first tutorial I am making for the purposes of letting you guys in on my design process and hopefully so you can employ these same techniques in your 3D models. This will also serve as a way of me documenting all my tools and tricks so I myself can even comeback and look at how I approached different design considerations.
As you have noticed, I model a lot things from video games and TV shows that I enjoy. This means that I usually have plenty of reference images at my disposal, however there are certain things I can do to make those reference images more useful and the design process quicker and easier.
For this tutorial I will be using Onshape as my CAD software. It is free and in-browser and has all the tools I need to create complex 3D models. If you are using a different CAD software I'm sure it has similar if not identical tools that you can use to mirror these tutorials.
Importing an Image
You want to start a new sketch and select this drop down menu
From the drop down you want to select insert image
You will then import the image you want to use and select it from the above menu
You will then insert it into the sketch. First you will simply select some point and give the image some arbitrary boundary. It is most likely a good idea to define the dimensions of your image. My estimates below are based on my estimates of Finn's Sword, Scarlett. It is also best practice, while doing this, to make sure you are looking directly at your sketch plane, this can be done in two ways.
Right click on open space a select view normal to sketch plane
Click the plane you want to view on the cube in the top right
Now that you have your image you can now create your model using the image as references for feature location, size, etc. This is a very useful tool for any model making but there are some additional things we can to do get the most out of our reference images.
Using multiple images
While using a singular image is massively helpful for things like proportions, length, writing, etc. Using multiple images can help with making 3d models. Below I modeled another one of Finn's swords. What you can see is that I found pictures of a front profile and a right profile of the sword. I center and align them as best I could. Because it is a relatively simple shape, I am able to use the front profile to create the main shape of the sword and the right profile to estimate thickness. Obviously this method isn't perfect since this is a cartoon and the sword changes length depending on the frame, but this does come in handy if you can find actual profile drawings or schematics of the thing you are trying to model.
Angling your image
I was lucky enough to find two images where the sword is oriented straight up. However let's say that like my image of Scarlett, the object in question is not in a perfect CAD drawing orientation. If you want to avoid doing trigonometry you can also reorient your image.
When you initially place your image, all the lines are automatically perpendicular to each other and the bottom line has the horizontal feature.
You'll want to click the bottom line, then click the small box featuring the horizontal line and press your delete/backspace key.
Now that the bottom line is no longer defined as horizontal once you define a location of one of your four corners, you will be able to rotate that image around that point.
You can see in this image when I initially imported the image into the sketch, I attached the initial point to the origin. I then added a horizontal line that I could use to define the orientation of my image. Again I defined the size of the image to fully define the sketch.
Now that I've reoriented my image, the shaft is now vertical and it made creating this glaive much easier.
Using images to define advanced curvature (Splines)
Now that you know how to import images into your document, there is one more tool that I feel is very important for you to know before you get started.
Here we have Orcrist, a blade that it much more complex than the two swords I've mentioned earlier. One way to get the curve of the blade for use with Lofts, Sweeps, etc. (Check out my Lofting/blade making tutorial for more info on that), is to use splines.
Splines essentially allows you to continually drop points. As you drop points, Onshape will continually connect every point you drop with one continuous curve that travels through all points. You will double click in order to drop the final point. Using one smooth curve is often preferable to trying to make this edge using several three point arcs, all using tangent relationships.
Additionally, once the spline is down you may move the individual points around to adjust the curve.
Another thing you should be wary of is that if you start to approach a tighter curve, you should drop more points to insure that the curve is able to easily adjust without ballooning outwards near the beginning. You can see this technique here, as well as the fact that I essentially zoom in on my reference images and drop points along the edge I'm referencing.
*in this image it appears my curves don't line up because I'm not viewing the sketch straight on. Make sure to that your view is always normal to the sketch plane *see above, before creating your splines.
I hope this tutorial was useful to you and will help you create your favorite props from your favorite media. Next I will be exploring how to use 3D meshes (.STLs .OBJs etc.) as reference for recreating and modifying very complex and accurate 3D models.
You can find that tutorial here.