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4. Alien Character – Creating a Proper Topology and Transferring the Sculpt Details
Now that we have seen a few basic techniques, we are going to see a practical case by working on our little alien character sculpture.
Before starting the retopology of our little character that came from distant worlds, we must prepare the working environment for the method that we will use. There are several possibilities in Blender to do a retopology, including with very good add-ons (Retopology MT and Retopology Tools, for example). We will not use them here; instead we will focus mainly on internal Blender tools.
- We will start by placing the cursor at the center of our sculpted mesh. For this, we will select the mesh and press Shift + S to open the snap menu. Then, we will choose the Cursor to Selected option.
- We will then create a plane in the Object Mode (pressing Shift + A and selecting Mesh | Plane) that we will place in front of the eyes. This new object that has been created is going to be the new mesh for our character. We rename it as
Alien_Retopo. - In the Edit Mode, we will bisect the plane, delete the vertices on the left-hand side, and then we will add a Mirror Modifier. Don't forget to check the Clipping option.
- We need to make a transparent shader that will allow us to work comfortably in order to visualize the mesh. In the Material menu, we will check the New button. It's also good to name this; in our case, it is
M_Retopo. This way, we can look through our polygons and check the Transparency option with an Alpha value of0.208. - We will then go in the GLSL mode in the Shading menu of the right panel of the 3D viewport (N). This allows us to visualize the new material that has been created.
- We will also check the Backface Culling option just below the Shading menu to avoid being too bothered by the rear faces.
- We switch to the Texture shading mode in the corresponding drop-down menu located in the 3D view header.
- After this, we need to add a Hemi light (by pressing Shift + A and selecting Lamp | Hemi) that is to be placed just above the 3D model in the direction of the ground. We will set its energy value to 1.
- We will activate Xray in the Properties editor in the Object tab under the Display subpanel.
- For our comfort, we need to change the size of the vertices. For this, we will go to File | User Preferences | Theme | 3DView | Vertex Size. We will enter a value of 6.
- In the User Preferences menu, we will check that the F2 add-on is activated.
- In the 3D viewport header bar, we will activate Snap (it looks like a little magnet) in Face Mode (just on the right-hand side of the snap icon).
- We still have to activate the buttons located a little more on the right-hand side called as Project Individual Elements on the surface of other objects and Snap onto itself. Let the mouse hover over a button for a moment so that you can see its tooltip appear.
Now we can start to build the new topology.
Let's start our retopology with the head of our alien character:
- In the Edit Mode, we will snap our first polygon with the Grab tool (G).
- We will then begin to form the first face loop around the eyes. We will select the edge on the right-hand side of the plane and pressing Ctrl and a left-click, we will create new polygons in sequence on the surface of the sculpted mesh. There is no need to be very accurate while tracing the first face loop. We will be able to reposition the vertices and adjust the number of polygons thereafter. So, we will make the first face loop, which passes through the eyebrow, the cheek, and joins the symmetry axis right at the nose. At the corner of the eye, we need to be careful while placing an edge that extends the diagonal direction of the eye (refer step 2 in the following screenshot). This face loop is called the mask.
- We will then add two edge loops (Ctrl + R). Try to equalize as much as possible the size and the distribution of the polygons. We will reposition the vertices to have a rounded shape (refer to step 3 in the preceding screenshot). For our selected components snap on to the sculpture, we have to move them with the Grab tool (G). Remember to do this often, but only with the components that directly face your point of view.
- We will add an edge loop to the nose in order to have enough polygons to better define the outline shape. We will have a 28-face face loop.
- We will join the nose with the new polygons (refer to step 4 in the following screenshot).
- To save time, you can start making a shape with a few big polygons to cover a large area that you want to work on. You can then define the number of cuts that you need and snap the topology, rather than make many little polygons one after the other.
Try to follow the shape of the sculpted mesh as much as possible.
Note
F2 add-on
We mentioned this while preparing the environment. F2 is an essential add-on in Blender that allows us to quickly create faces.
Between the two rows of the edges, the F2 add-on can generate the missing faces. You can also generate a face by selecting one vertex on the intersection of two faces by pressing F. Repeat the process to quickly make a face loop, and remember to weld them (select the polygons, and then press W and select Remove doubles).
You can also generate the face loops in the edge mode. You need to select a starting edge (the one to the left and perpendicular to the x axis according to the following screenshot) by pressing F. The sense of creation of a face can be determined by the placement of the mouse if the starting edge is at the center of the face loop that is to be created.
- We can see that we have a pole. We will avoid making it too visible, so we will place it under the eyebrow.
- We complete the topology of the upper nose with a polygon reduction on the forehead (refer to step 5 in the preceding screenshot).
- Now, we will select the edge loop that bypasses the eye, and we do an extrusion by changing the scale (E and S). We will then place the vertices on the outline of the eye (G). We will have a 24-face face loop (refer to step 6 of the preceding screenshot).
- We will add two edge loops (Ctrl + R) around the eye that we will reposition correctly (G). A first edge loop takes the shape of the eye, marking the fold with the eyebrow. A second edge loop makes the link between the two shapes.
- At the left outer corner of the eye, we will tighten the vertices. We will take care to have a conical shape that spreads outwards (refer to step 7 in the preceding screenshot).
- Now, we create a face loop from the nose to the chin. It is called the nasolabial loop. We will add the polygons using F2 (by selecting a corner vertex and pressing F). Just like the eye, we extrude an edge and form a face loop from it that follows the circular shape of the mouth. We will have a 16-face face-loop (refer to step 8 of the preceding screenshot).
- We will add a face loop that comes around the nose. This allows us to define the nose. Remember to slightly bring the edges at the bottom to the septum of the nose. We will have a 9-face face loop (refer to step 9 of the preceding screenshot).
- We will create the topology that forms the top and bottom of the nose. We will have a 6-face face loop (refer to step 10 of the preceding screenshot).
- Once the nose shape is outlined, we will begin the ala of the nose. We will extrude a face loop that starts from the top of the nose down to the bottom of the nose, avoiding the nostril. This arrangement allows us to better create the shape of the nostril loop (refer to step 11 of the preceding screenshot).
- We will extrude the edge loop of the nostril with a scale transformation (E and S). We will then close the hole by connecting the edges (refer to step 12 of the preceding screenshot). If you don't have enough edges to make four-sided polygons, you can use a triangle. It must be as hidden as possible.
- We will start from the corner of the nose to make a face loop that goes under the mouth.
- We will then close this part by following the shape of the lips. Take care to slightly pinch the corner of the mouth. The topology must be as symmetrical as possible between the top and bottom of the mouth in order to connect them later. We will have a 14-face mirrored face loop (refer to step 13 of the preceding screenshot).
- We will continue around the mouth by adding a polygon strip above the chin (see 14 and 15 in the preceding screenshot).
- Now, we will make the face loop of the jaw, which ascends to make the contour of the face. We have a 22-face mirrored face loop (refer to step 15 of the preceding screenshot). We need to align the faces correctly for an easy connection and close the area of the jaw (refer to step 16 of the preceding screenshot).
- We will make the contour of the antennas with an extruded vertex on the top of the forehead in a circular manner (refer to step 17 of the preceding screenshot).
- We will then continue to form the polygons of the forehead, in line with what was done, by making a reduction in the number of faces, avoiding the antennas (refer to step 18 of the preceding screenshot).
- We will select three edges on the temples and create a polygon strip that follows the back of the head. We need enough faces to have a nice rounded.
- We will then select the edge located at the jaw, and we will continue to make the topology of the back of the head (refer to step 20 of the preceding screenshot).
- Now that the face strips are facing each other, we can fill the missing topology with the Fill and Loop Cut tools. (Refer to step 21 of the preceding screenshot.)
- We will continue to make the faces on the back of the head in the same way. We will form an angle to close the top of the head later more easily. (Refer to step 22 of the following screenshot.)
Note
The Smooth option
In order to have a topology as homogeneous as possible, we can use the Smooth option of the Specials menu (W). This allows us to relax the polygons. We first need to select the faces we want to modify (C). Be careful as you have to snap them after the process (G), so select only the visible faces in the view.
We now need to close the topology of the top of the head. We must pay attention to respect the number of edge loops created previously. You can apply the smooth option to quickly relax some misaligned faces.
Now we are going to make the antennas that require another technique:
- We will duplicate the edge loop situated at the base of the antenna already created to make a new object (by pressing P and select Selection).
- We need to deactivate the Snap option and the Project Individual Elements option.
- We can extrude this new object following the shape of the antenna. The polygons must completely cover the surface of the sculpted mesh. You can set Wireframe Shading Mode in order to view your geometry better.
- Once we get the desired topology, we add Shrinkwrap modifier and select the sculpted mesh in the Target parameter, called Body. This modifier allows us to snap a mesh on another.
- We must apply the modifier by clicking on Apply button, and then we will join it back to our other piece of geometry. For this, we select the mesh of the antenna, then the mesh of the head, and we press Ctrl + J.
- As we want to snap our components on the sculpture again, we will restore the Snap and Project Individual Elements options.
- We can add a few edge loops to the antenna in order to get a good enough shape.
- We will connect the faces in the back of the head in continuity with the topology already done.
- From the angle of the jaw, we will create a face loop that ends at the symmetry axis on same level of the glottis (refer to step 25 of the following image).
- We will then connect the face loop to the chin by adding enough edges. We need to connect the entire underside of the jaw. We have a 10-face face strip (refer to step 26 of the following screenshot).
- This area forms a triangular shape. We need to make loops to reduce the number of polygons around the chin. We can easily reduce the polygon flow by redirecting the loops on the axis of the symmetry (refer to step 27 of the following screenshot).
- To better visualize your polygons, you can hide the ones that you do not want to see. You can use the H shortcut. Press Alt + H to make them reappear.
We will continue this retopology with the neck.
- We will make a small polygon reduction at the back of the neck in order to lighten the density a little bit. We only need to progressively extrude the polygons along the neck. We will then align the polygons on the collar. We slightly pinch the edges to restore the volume of the collar outline.
The challenge is to properly harmonize the polygon flow along the front and the rear.
- We will continue to extrude to the clavicles. Using loops, we will add a polygon row in the middle of the nape, and we will reduce one on the sternum (refer step 28 of the preceding screenshot).
- There is an important face loop to place in case we want to animate the arms later. It follows the lower pectorals and shoulders muscles. We will have a 20-face mirrored face loop (refer to step 31 of the preceding screenshot).
- We will make another important face loop that goes vertically around the shoulder and passes under the arm. We will have a 16-face mirrored face loop (refer to step 32 of the preceding screenshot).
- Therefore, we will connect the polygons to form the chest and the upper back. On the shoulder, a new face loop links the polygons that intersect vertically and horizontally (refer to step 33 of the preceding screenshot).
- We will extend the topology straight to the pelvis in a cylindrical manner. There is no particular difficulty on this part (refer to steps 35 and 36 of the preceding screenshot).
- We end the hip with a strip of polygon that joins the axis of symmetry and we will create the crotch by connecting the buttocks polygons. Don't add too many edge loops, just what is needed. We will have a 6-face strip to make the connection (refer to step 37 of the preceding screenshot).
- Now, we will make a face loop that follows the shape of the buttocks. This face loop allows us to have a good deformation when animating the legs. To connect the vertical polygons that come from the back, we will make a second face loop right in this area (refer to step 38 of the preceding screenshot).
It is time to make the topology of the arms. Considering they are quite thin and not very muscular, we are going to use the same technique that we used for the antennas.
- This time we will add a 10-face cylinder (Shift + A) positioned around the arm. Be careful to match the number of faces on the shoulder (refer to step 39 of the preceding screenshot).
- To facilitate the visualization of two meshes, we will parent our semitransparent material by first selecting our retopology, and then selecting our new cylinder by pressing Ctrl + L and selecting Materials.
- We will add a Shrinkwrap modifier with the sculpted mesh as a target.
- We need enough polygons to get a sufficiently smooth shape. We will bring, little more loops on the elbow in case we need to animate the arm later so that it will bend appropriately.
- As for the antennas, we will apply the Shrinkwrap modifier in order to freeze the new shape. We will then join the arm to the rest of the body (Ctrl + J).
- Now that we have only one mesh, let's connect the arm to the shoulder by selecting the two opening loops and by bridging them together (by pressing W and selecting Bridge Edge Loop). Since we have the same number of vertices on the two sides, Bridge must work fine. We will then need to adjust the topology by adding some edge loops here and there. Don't forget to snap back the vertices on the sculpture (refer to step 40 in the preceding screenshot).
Let's start the hand. It is a particularly delicate part of the anatomy to do:
- We will start by doing the fingers using an extruded circle again and the Shrinkwrap modifier for each finger. This is the same technique used for the antennas and the arm. This time, we need to extrude a 10-edge circle for each finger. This number is important because we need to have enough polygons for the hand. Pay attention to the orientation of the thumb (refer to step 41 in the preceding screenshot).
- Once this is done, each finger is closed by joining six four-sided polygons. Our character has only two phalanges by the finger, so be sure to place three cuts around each of them if you want to properly animate the fingers later.
- Then, we will make some of the important face loops of the palm. There is a 10-face face loop that passes around the thumb (the thenar muscles). There is a 14-face face-loop on the opposite side of the hand near the little finger (the hypothenar eminence) (refer to step 42 in the following screenshot).
- We will create a face strip in order to accentuate the basis of the fingers. It is also important to leave a space between each finger (refer to step 43 in the preceding screenshot).
- Now, all the face loops have to be connected. We have the needed density to only use four-sided polygons without too much difficulty. Train yourself to fill holes with the number of polygons that you have. In this case, we can't change the number of polygons that wraps around each finger (ten in our case) (refer to step 44 in the preceding screenshot).
- We will add a few more horizontal edge loops around the phalanges in order to have a smooth shape.
We are going to finish this retopology with the legs. Let's begin with the thigh:
- We will select the edge that makes the outline of the leg and extrude it to the knee (E). As before, we will add a few edge loops (Ctrl + R), and then adjust and snap the topology on the surface of the sculpted mesh. We could have used the technique used for the antennas and arms with a cylinder but the thigh is wide enough and less complex (refer to steps 47 and 48 in the preceding screenshots).
- We will add an edge loop a little tighter near the knee.
- We can see that the boots are just above the knees, so we will make two edge loops that stick to the relief (refer to step 49 in the preceding screenshot).
- On the front of the knee, there is a loop that will reduce the number of polygons on the shin. It goes up and down along the thigh (refer to step 50 in the preceding screenshot).
- There is another face loop to be created that will follow the rounded shape of the boot at the knee. It goes up toward the thigh (refer to step 51 in the preceding screenshot).
- We must create the missing polygons on the top of the boot in line with what was done until the opening of the calf.
- This opening of the boot requires two face loops that allow us to maintain the hole. We must pay attention that it is easily connectable between the top and bottom. This looks like the circular topology case that we had analyzed before. We have two 18-face mirrored face loops.
- We will continue the retopology by creating a loop that goes under the heel and connects with the upper leg (refer to step 52 in the preceding screenshot).
- Let's go back to the front of the thigh and continue to form a strip of polygon that goes around the foot and forms a long face loop. It goes through the knee. This allows us to control the polygon flow by adapting it to the shape. We just need to keep the same number of polygons on both sides of that face loop in order to connect them properly (refer to step 53 in the preceding screenshot).
- A final important loop remains to be made. This is located under the foot. It follows the outline of the plantar arch with a 20-face face loop aligned so that we can easily connect it to the rest of the foot (refer to step 54 of the preceding screenshot).
- We still have to connect the inside of this underfoot face loop. To move from one row to three rows of polygons along the length of the foot, we must create a face loop by cutting the faces at the ends of the feet (refer to step 55 of the preceding screenshot).
The retopology of this little character is now over. We complete a mesh that offers many possibilities, such as creating textures or doing animations. All of this couldn't be envisaged with a very high polygon density and sculpted 3D model. Having a few polygons will facilitate the process. The important thing now is to get the small details that we had sculpted back on our mesh that we can describe as a low poly mesh. For this, we must discover a process called UV's unwrapping.
A presentation of each important face-loops of the alien
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