In the first part of the series we created the high poly model of the fire extinguisher, and now we'll optimize that high poly model to create a low poly model in a procedural way. (Actually it’s a next-gen video game art process.)
While creating our high poly, detailed model. We take care when creating the mesh flow, details and adding smoothness, but it's not always possible to work with limited polygons. Sometimes the number of polygons goes beyond the limit.
So for next-gen game models, we create a high res model first and then we optimize it to a low res state by removing the supporting edges and unwanted geometry. In this part of the tutorial we'll employ that technique, and learn how to optimize and turn a high poly mesh into a low poly model.
1. Cloning and Scene Setup
We have already created the high poly model of the fire extinguisher in the previous part of the tutorial. So, let’s convert it to the game ready low poly model. For security purposes, we'll start by saving a copy of the high res model. So, with the fire extinguisher model selected, Right Click and select the Clone option from the fly out menu.
This opens the Clone Options window. Here select the Copy option and change the mesh's name to LO_Mesh.
Now click on the Manage Layers icon in the menu bar to open the Layer Manager. Here click on the Create New Layer button to make a new layer.
Rename the new layer Lo_Mesh. Now with the Lo_Mesh object selected in the viewport, Right Click on the Lo_Mesh layer and then click on Add Selected Objects. Now the Lo_ Mesh model is part of Lo_Mesh layer.
Now click on the Hide button in front of the Hi_Mesh. So we can only see the Lo_Mesh in the viewport.
2. Removing Unwanted Edges
Before we start low poly modeling, let's take a look at the difference between high and low poly meshes. In the image below, you can see two meshes. The right one has supporting edges and is a high poly mesh, and the other one on the left side is a low poly mesh. If you remove the supporting edges from the high poly mesh, you can easily create a basic low poly model.
Now let’s start converting the high poly mesh into a low poly mesh. To start, select the supporting edge loops which we added when making the high poly model, and press Control-Backspace to remove these edges from the mesh.
Now select other supporting edge loops, do a Right Click and select Remove from the menu to remove the edges. This is an alternate way to remove the edges.
Select these edges which really don't effect the model's shape, and press on the Loop button in the Editable Poly Selection options.
You can see that these edge loops do not affect the model's overall shape. So Right Click and select Remove (or press Control-Backspace) to remove the selected edge loops.
Now remove the unwanted edges from the main body of the model. Select all the indicated edges shown below, and remove them from the mesh.
Let's see how we can optimize the mesh further for the low poly. First, select one of the middle edges inside the lower groove and click Ring.
Now you can see the complete edge ring is selected.
Right Click and this time select the Collapse option from the menu.
This will collapse the selected edge ring and reduce the amount of edge loops. This is now the shape required for the low poly.
Now let's start working on the bottom part. Select all the bottom faces and press the Delete key to delete the selected faces.
Now we have to cap the bottom of the fire extinguisher. So, first select the border edges that run around the bottom hole.
Then de-select the two edges indicated in the image below.
Now click on the Bridge button.
The bottom of the mesh should now look like this. The Bridge command attaches all the faces together automatically and keeps the edges straight.
Now select this edge ring and then Right Click and select the Collapse command to optimize the mesh.
With the indicated edge rings on the handle selected, Right Click and select Collapse.
In this step we will touch on some of the new modeling options in 3ds Max. According to the poly distribution, there are lots of edges on the handle which are not required for a low poly model, so we'll get rid of them. First, open the Graphite Modeling Tools. While in Edge selection mode, go to the Modify Selection menu. There you will see an option called Dot Gap. Increase its value to 2. With the help of the Dot Gap tool , you can extend the gaps in between edge loops or edge rings.
Now if you click on the Dot Loop tool, you can select edge loops with a gap in between.
Here is an image of the selected edges. Notice the gap of 2 edges in between the selected edges.
Now Right Click in the viewport and select the Collapse option.
Now we will attach two different meshes into one. Select the faces indicated in the image below and then Delete those faces.
Next, select the two indicated edges and press the Bridge button to fill the gap in between.
Now while in Border selection mode, select the border around the hole.
De-select the indicated edges.
And press the Cap button to fill the hole.
Now we have to connect all the vertices together on the faces which are not triangle or quad. So with the indicated vertices selected, Right Click and select the Connect option to connect the vertices together.
We have an unused edge loop indicated below by green line. Whether we remove this edge loop or not, it is not going to affect the mesh. So just use the Target Weld option to weld the vertices to their corresponding outer vertices, which are marked by red arrows.
Perform the same operation on all the vertices present on the belt (it should look like this after connecting all the vertices.)
3. Attach the Floating Mesh to the Main Body
In this step we'll attach the front floating mesh to the main body mesh. Select the indicated edges as shown in the image, and then Right Click and choose Connect, to connect the edges and align them to the green mark shown.
A solid mesh helps with unwrapping and saving the blank texture page. We create the floating meshes mostly on the high-res model, because it’s easy to get the required shape in high poly. But with a low-res model, we need to make it solid or one single element. So here the up sided tapered shape is floating and is not attached with the cylinder on the element level.
Select the side shape using Element selection. And then hide it by Control-Right Clicking and choosing Hide.
After hiding the floating mesh, switch to Polygon mode and select the faces that were underneath it.
Delete the selected faces, and you'll get a shape like this.
Now we'll attach the meshes (the floating mesh and main body) together. First of all, Unhide the floating mesh by Control-Right Clicking and choosing Unhide All ( which we hid in the previous step.) Then switch to Border mode, and select the border of both meshes.
Right Click in the viewport and select the Convert to Vertex option.
Now Right Click in the viewport and select Weld, to weld all the open vertices.
Select the vertices shown and connect them, by Right Clicking and selecting the Connect option.
This creates some unwanted edges. So select the edges as shown in the image, and press Backspace to remove them from the mesh.
Now you should have a mesh like this. It has become a single object now and you can select it as a single element.
4. Adding Supporting Edges
This pipe looks very edgy. We need to add some edge loops in between the current edges. Go to the Graphite Modeling Tools and find the Flow Connect option. Flow Connect is a tool which adjusts a new loops' position to fit the shape of the surrounding mesh.
The pipe looks like this after applying Flow Connect to the curved edges.
To optimize the nozzle mesh, select the edge ring on the inner part and Collapse it (Right Click > Collapse).
Follow the same process here. Select the edge ring and Collapse.
Select the indicated edge loops shown in the image, and Collapse them as well.
You can see how light the mesh has became after collapsing the edge loops.
Select the same edge loops on the pipe (which were selected in the previous step.) Right Click in the viewport and Collapse these edges.
You can see there are 18 sides in the top ring. When we created the high poly model, we applied a Turbosmooth modifier to make it smoother. But here we need a good roundness without applying Turbosmooth, because we are making a low poly model. So create a new Torus object, with the same Radius as the old one. But this time use 24 Segments and 8 Sides. and then replace the old one with it.
5. Applying Smoothing Groups to Finalize the Low Poly Model
Our low-res model is now complete. We now need to apply smoothing groups to the mesh. Let’s talk a bit about Smoothing Groups. For a low poly model, smoothing groups are a very essential step to be taken. If we apply a polygon smoothing group to the faces of the model, they will look smooth when shaded. Have a look at the example below. These are the same model, but the right model looks much smoother than the left side one. However both have the same number of faces, but the right side model’s faces have a smoothing group applied.
Jump into Polygon selection mode and select all the faces on the fire extinguisher model. Go to the Polygon Smoothing Groups rollout in the Modifier panel, and click on the Clear All option, to clear any previous smoothing groups from the object.
Now click on Auto Smooth, and it will create smoothing groups automatically.
With the faces of the handle selected, Clear All the previous smoothing groups and then click on any of the numbered groups listed.
Follow the same process for the top ring to apply a smoothing group to the faces.
Now that we have applied smoothing groups, here is the final low poly version of the fire extinguisher model ready for the next step.