Create an akira-style bike model In Vr
Learn how to intuitively create a prototype model in virtual reality with Gravity Sketch
the Holy Grail of digital creation is transferring analogue skill sets, such as drawing and sculpting, into a seamless digital experience. But what if you could combine the skills learned in 3D applications, such as the manipulation of vertices, edges and faces, in a virtual studio where models can be manipulated by pulling and grabbing with your hands?
The virtual reality creation application Gravity Sketch allows artists to do just that using a new paradigm for 3D modelling. It enables you to sketch in a 3D space and then augment with planes and polygons using a unique and intuitive toolset.
While still in its early days with version one, Gravity Sketch offers artists who are new to 3D a new and unique method of modelling, which allows artists of any skill level to create complex shapes quickly and easily.
In this tutorial I will create a model based on the iconic motorbike from the classic anime
Akira, as there have been many variations of its form since its inception as a 2D cel drawing. Therefore it is ideally suited for Gravity Sketch, allowing an environment where a new take on this iconic shape can be created. The tutorial will walk you through how to set up a scene and the tools needed to create a model like this, which will provide any artist with a footing in this amazing new creation software.
01 CREATE A BASE FORM IN 3D
As the bike has a unique proportion with its large wheels and reclined rider position, it is a good idea to block out a simple shape in a traditional content creation application such as Cinema 4D. A simple maquette model was downloaded for free from Turbosquid, and then manipulated into the position of the rider using a background image from the internet as reference.
02 PREPARE THE MODEL FOR EXPORTING
Gravity Sketch can import models using the OBJ format. To export the model from Cinema 4D make sure to check that ‘Swap Y and Z Axes’ is ticked to ensure Gravity Sketch will orient the model as seen in the Cinema 4D viewport. Using trial and error, it seems that exporting using the centimetres option works best with importing into Gravity Sketch; if other measurements are used there can be issues with materials. Make sure to export the file to the Import Library folder of the Documents>gravity Sketch folder.
03 ENTER GRAVITY SKETCH
On initial launch, Gravity Sketch appears as a white infinite space, but there are other environments to choose from. The Touch Controller appearance can be modified, but that can have an impact on performance, especially if using them in transparent mode. So it is probably best to stick with the default look, unless using the latest hardware.
04 THE RIGHT-HAND ‘CREATE’ CONTROLLER
The right-hand controller is the ‘Create’ controller. Think of it as a pen nib for sketching (hand functions can be switched if left-handed), and also the primary manipulator of objects. The red sphere that surrounds the controller is the grip sphere, used to select objects that have been created. On the Oculus Rift, the radius of both the ‘pen’ and the ‘grip’ is controlled by the right joystick – left and right for pen size and forwards and backwards for the grip. The remaining buttons are used for single-step undo and selecting colour.
05 THE LEFT-HAND ‘TOOL’ CONTROLLER
The other controller, in this case the left-hand controller, contains many more tools. The triggers act as a right-click, the joystick acts as a backward and forwards history tool for editing, but it is the two top buttons that hold all the main tools. Scene and settings are accessed via the blue button and the artistic tool selection is accessed through the purple button.
06 ACCESS MENUS
Using the Tool controller, select the blue button and go to the Prefabs selection, which looks like a dressmakers dummy. Select the middle bottom icon to choose the ‘Import OBJ files’ command. To select anything within Gravity Sketch, use the Create controller by simply pointing at the selection, whereupon a virtual pointer will appear from the front of the Create controller.
07 BRING IN THE OBJ
Once the OBJ file has been selected (making sure that the file had been correctly placed in the Import Library in Documents>gravity Sketch), the name should be replaced by a small 3D representation of the model. Move the Create controller close to it, and when the OBJ model is surrounded by a purple line pull the trigger on the Create controller to pull it out of the menu.
08 SET THE MODEL IN THE SCENE
The model is tiny when it is brought into Gravity Sketch, and it can be picked up and dropped anywhere in the space by placing the Create controller near it. When the purple line surrounds the model, pull the side Create trigger and the controller disappears, and the selected element can be manipulated using the Create hand. Just release the trigger to let go of the selected object where you want it. Get used to dropping and picking the object up and reorientating it. This is guaranteed to bring a smile to the face of any 3D artist.
09 SCALE THE MODEL
Bring both controllers up to the model, select the Create trigger first when the model turns purple, then the Tool trigger, and pull outwards with both hands. The model should scale up with the physical distance of the hands. This scaling also works with the environment as well, and the scene can be orientated and scaled by pulling the second trigger of the Tool hand first.
10 USE THE SETTINGS FOR SYMMETRY
The easiest way to create a sketch prototype is to use a symmetrical environment. Select the gears icon in the settings menu when the blue button is pressed on the Tool controller. Switch on the Mirror tool by using the Create controller to ‘drag’ the on-off slider to the right. A green and red crosshair should appear: this is the line of symmetry and our model needs to be placed across it.
11 PULL OUT MENUS AND THE GRID
We may need access to some other settings, such as the Grid which snaps objects to a 3D grid visible around the Create hand. The grid spacing can be adjusted and switched off from the same panel as the Mirror setting. To make sure the grid is always available just reach for it with the Create controller and a purple line will appear, allowing the panel to be pulled into the workspace.
12 CREATE WORKING LAYERS AND ADJUST THE ENVIRONMENT
Press the blue button again to pop up the layers icon, which is three flat cubes, and pull the layers panel into the environment. Use the Create tool to press the larger ‘+’ button twice to create new layers, and then touch a name of a layer to bring up the virtual keyboard. Name the layers as required for images, the base model and sketches. You may also notice another panel called Workspaces: this can change the environment by choosing the different spheres and there is a torch available for adjusting the lighting as desired.
13 IMPORT IMAGES
Press the blue button menu again (if it has closed) to select the Reference Images icon. Choose the images that are required using the same purple-lined selection method with the Create tool and pull the images into the workspace. To place the images into the correct layer pull the images into the large box beside the layer name. This should snap images back to where they were picked up.
14 WORK WITH LAYERS AND ORIENTATE THE SCENE
Use the same methodology of selecting and dragging into the correct layer ‘box’ to place the imported OBJ into the base model layer. The visibility of layers can be adjusted via the circle and line sliders. Orient the scene to begin sketching; in my case making the model appear approximately a metre across and at waist height works best. With the Image Layer active, move and scale the reference images using the same methodology of the controller ‘grip and pull’ to place the images around the scene.
15 PICK A COLOUR FOR SKETCHING
Making sure that the ‘sketches’ layer is selected, press the Colour Picker button on the Create tool to pick a colour and material option. In this case Red Reflective is probably best as the purpose of this layer is to sketch out the primary forms. Press the purple tool button to make sure the desired Create tool is chosen – in this case it is the top line tool – and start sketching.
16 START SKETCHING THE BASIC SHAPE
To sketch, pull the trigger on the Create controller. When a line is finished, let go of the trigger. At this stage just block out the key shapes, as the actual model will be refined at a later stage. As symmetry is selected a mirror of the sketch should appear on the other side. When sketching the seat and the glass make sure to choose an appropriate colour.
17 LEARN TO WALK AROUND
Make the most of working in VR by walking around the model as it is being sketched, as this really helps when trying to create a sketch line. Remember that the Undo button is available on the Create controller and the History can be rotated on the Tool joystick to move back and forward through the sketched line creation. Use the ‘grip and pull’ technique to shrink and enlarge the scene to allow any part of the model to be accessed in detail, and to also allow a bird’s eye view to check the overall form in seconds.
18 START TO REFINE THE SKETCHES
To refine a sketch line, highlight it with the Create tool. Any sketch line can be moved and scaled as needed, and the Tool hand will have a small icon of spheres connected by a line over the blue button; press this to enter the line edit mode. A new tool palette will appear with a button to smooth the selected sketch by reducing the number of control points.
19 WORK WITH CONTROL POINTS
Refine control points by using the scale and rotate method to get ‘within’ the model. Moving the Create grip sphere, highlighted control points can be moved. Activating the Snap function will allow selected control points to snap to points on inactive sketches. To add a control point back move the Create tool over the dotted line, pull the trigger, then press the tick on the Tool hand.
20 BUILD THE WHEELS
Once the sketching is finished create a new layer for the modelled elements. Lock the other layers and slide back the opacity to start creating the model elements. To create the wheels, select the Revolve tool from the Tool controller and with the scene snap and grid on, use the Tool hand to place the ‘centre’ line of the wheel in the correct position. Then use the Create tool to pull out the wheel either as a freehand sketch or as a trigger-release curve. Create one revolve for the tyre and another for the wheel hub.
21 REFINE THE WHEEL SHAPE AND GROUP
Revolve objects can be adjusted just the same as sketches, by clicking the blue button on the Tool hand to access and simplify the control points. With Snap turned on, the hole in the hub can be easily sealed, and the curve of the hub and tyre profile adjusted as required. To create the rear tyre, exit point mode, then select and ‘group’ the hub and tyre by selecting them both and pressing the purple button on the Tool controller button, which should now show the hexagonal tiled ‘group’ icon.
22 DUPLICATE A GROUP OR SHAPE
To duplicate the wheel group select it and pull the Create trigger once to leave a copy, then move the wheel object to the rear of the bike and drop it. Either wheel can be manipulated and edited separately. Double-check the wheels to make sure that a second copy has not been left. To delete an unwanted copy, select it and press the red undo button on the Create controller.
23 USE STROKES AS MODELLING GUIDES
Create a new layer called ‘Guides’ and select the Stroke tool to start creating simple guides to define the edge of the main components of the bike. Make these a separate colour from the model so that they can be easily seen. It is usually best to work in point mode for the creation of guides as it allows more control, using a trigger pull to create a new point.
24 SURFACE USING THE GUIDES
Once guides have been set at the desired edge locations, surfaces can be created by using the Curved Surface tool. This tool creates a surface – which if the Bridge Curves option is selected can create a surface between two guide strokes. In fact, anywhere a stroke is highlighted in red it denotes the curve as being suitable to create a surface from. The tension indicator in the Curved Surface settings shows how much of a curve will be created in the middle of the surface, and can be adjusted as needed.
25 PULL OUT SURFACES
Use both the controller triggers to pull out a surface. Placing a surface can take a bit of trial and error, but like most other elements within Gravity Sketch, a surface can be edited and its control points accessed. With surfaces, edges can also be accessed by using the Create controller joystick when in edit mode where they show up as a green line.
26 USE VOLUMES
While using the guide and surface methodology is good for creating certain elements such as the fairing, for ‘chunkier’ elements such as seat cushions and the fuel tanks this would be laborious. Use the Volume tool as an alternative for these kind of shapes. Again using the point mode offers the most control and keeping three control points tightly together can allow complex shapes to be created quickly and easily. Again volumes can be edited with the control point method.
27 CREATE SMALLER ELEMENTS
Details can be added as the sketching progresses. Handlebars for example are created by adding a primitive cylinder from the bottom Tool controller menu. Then, use the Revolve tool to create and copy the grip elements. Snapping does not work with primitive objects so this needs to be done by eye, however, it can always be adjusted afterwards by selecting the newly created copy.
28 ADD EXTRA DETAILS
Screws and bolts can be added by clever use of the Revolve and Stroke tool to create bespoke shapes that can be edited in position. Use the polar symmetry in the Stroke tool to create multiple objects from a central pivot and use the Revolve tool to make half and quarter lathed objects. Repeating these details and scaling them down can add character to the model.
29 PREPARE FOR EXPORT
Set the layers as needed to prepare for export. If the model is off the ground plane this will be carried through in the export, so be mindful of that. Press the blue button on the Tool controller and select the Save icon, then the centre arrow in the top row to export the model. Choosing FBX format is perfect for the model export required as it will keep the material assignments.
30 IMPORT THE GRAVITY SKETCH MODEL
When imported as an FBX into Cinema 4D the Gravity Sketch model is frozen, and has an object for each constituent part. This model could be perfect as a starting point for an animation or a more detailed model, which can make the most of the more advanced modelling features available within a full digital content creation application. As a starting point Gravity Sketch can be a unique and powerful tool for model sketching and prototyping and makes VR a valid creation tool for 3D artists.