Making a Low-poly Model Based on Images

I hope to give you a basic idea on low-poly image based modelling starting from a box. In this tutorial you will learn some important techniques which will be helpful for both low poly modelling and image based modelling. This tutorial mainly consists of UVW mapping and modelling. However you must have some knowledge on 3d max modelling to go ahead.
Before come to tutorial I’ll describe why I am going to start my tutorial from a box. That because most of the inorganic objects around us having the basic shape of box. If you didn’t understood, go through the following examples.
Similar to box – CPU casings, cupboards, UPSs, fridges, radios, etc.
Modified box – monitors, TVs, keyboards, speaker casings, sub woofers, etc.
If you still not believe in me wait until I am proving from this tutorial.
Ok, I am going to start my tutorial. As you all know box or cube have 6 square or rectangular sides (front, back, top, bottom, left and right sides). Find a digital camera, and take 6 photos of your selected object from each of these sides. However if it is hard to take a photo from bottom, leave that side.
I have selected a PC speaker, and followings are the photos I have taken from each sides.

Import all these photos to Photoshop and correct them by removing unwanted backgrounds and correcting perspective errors. Arrange all these corrected pictures in a single square Photoshop file (1024×1024 or 2048×2048).

Now you have completed making map for the model. Close Photoshop and open 3d max. Measure the maximum length, width and height of the model you are going to model (rough values may enough). Insert a box and adjust the length, width and height to values you have measured. Kept side segments as 1 and convert it to Editable Poly.
Open material editor, select one material slot and assign prepared map as Diffuse colour map. Turn on Show Map in Viewport button and apply the material to poly object. Now you will see the maps through viewport. However the maps may not in the correct way. To correct that, apply Unwrap UVW modifier to object and press edit button in the Parameters rollout to open Edit UVWs window. Place each UVW panel on the correct places of the map. (Hope you will able to do it by yourself. However don’t skip this step, it is very essential.)

Close Edit UVWs window, and ensure you have done it in the correct way. If you done it in the correct way, creases and other minor details should match with neighboring maps. When you satisfied about mapping, convert the object to editable Poly. Turn on Preserve UVs option under the Edit Geometry rollout. Now it will maintain the mappings without change when we edit the shape of the mesh.

Add 2-4 rings of edges around each side depending on the requirement. However you can add more lately if needed. Drag them to necessary places where the details will be. Draw simple lines across the basic shapes using Cut option. Delete all the faces which carry maps outside the object (backgrounds).

Detach polygon sets which should be in different levels/heights to separate to elements, and move them to correct places (you may use snap).

After moving all these polygon sets to different levels, the model should looks like little differ from its original box shape. Select all the vertices and weld them once to attach moved polygons to their new locations.
After that, look carefully around the remaining polygons. You may see some parts of the maps are duplicated. That because it is visible to camera in more than 1 side. But we need only one map for our need. Therefore, among these 2-3 maps, keep the most tangent one to the camera and delete the remainings.

Divide the faces to match with the neighboring faces and attached these vertices to already placed faces using target weld option. There is a one important thing you should keep in mind when you doing this. That is we have switched-on Preserve UVs in the Edit Geometry rollout. From that UVs are preserving until we move faces normal to face as well as moving edges and vertices on the surfaces within the boundary. However, it will go out if we move the edge of vertices out of the face or when we rotate faces. Therefore, if the UV go out when you moving the vertices, do that again by un-checking Preserve UVs option. Make sure to check the Preserve UVs option again after you have complete the task. That because, most of the time it works well with Preserve the UVs option. Repeat these steps to whale object until you get a closed object. Select all the vertices and weld once.

Now you should have the basic shape of your model. Now it’s time to make it realistic by making the surface curve. For that, you can use the existing edges and vertices first and add more and edit them later.

When you complete the task up to this, you should obtain a model somewhat similar to real model. But few other steps are remaining to complete to get a more realistic model. First of them is to correct UV mappings. If you carefully look at the model, you may see that some dark coloured edges are remaining in the model. 3 different methods can be used to remove these dork coloured edges.
Method 1 – Open the texture map in Photoshop and smuggle the edges of the maps a bit towards outside and save it.
Method 2 – apply Unwrap UVW modifier the model again and go to Edit UVs window. Now you can see how the new mapping looks like. Go to Vertex or Edge mode and drag edges/vertices you want correct little bit inwards. Close the Edit UVs window and see the different.
Method 3 – go to Cut mode and draw another edge little bit inside the existing edge, delete the faces in-between those two edges and weld the new vertices to existing vertices using Target Weld. Sometimes you may need to keep Preserve UVs option in off mode.
Remove all dark edges using any of the above 3 methods. I prefer the last, so I have used that.

Now it’s time to add details such as buttons and holes to the object. Mark the border of such item using cut Option (little inside to the place required). Attach the vertices of the new edge to vertices nearby. Select the boundary edges and Chamfer it to 2 rings. Select all the faces inside the smaller ring and move them inside or outside according to the requirement.

Repeat above steps to all the places essential. I hope you have received a good looking object. Render and see how it looks like.

Tags: 3d max, image based, low-poly, modeling, texture, tutorial