I've been trying without success to extract face features, for instance the mouth, from ARSCNFaceGeometry in order to change their color or add a different material.
I understand I need to create an SCNGeometry for which I have the SCNGeometrySource but haven't been able to create the SCNGeometryElement.
Have tried creating it from ARFaceAnchor in update(from faceGeometry: ARFaceGeometry) but so far have been unable.
Would really appreciate someone help
ARSCNFaceGeometry is a single mesh. If you want different areas of it to be different colors, your best bet is to apply a texture map (which you do in SceneKit by providing images for material property contents).
There’s no semantic information associated with the vertices in the mesh — that is, there’s nothing that says “this point is the tip of the nose, these points are the edge of the upper lip, etc”. But the mesh is topologically stable, so if you create a texture image that adds a bit of color around the lips or a lightning bolt over the eye or whatever, it’ll stay there as the face moves around.
If you need help getting started on painting a texture, there are a couple of things you could try:
Create a dummy texture first
Make a square image and fill it with a double gradient, such that the red and blue component for each pixel is based on the x and y coordinate of that pixel. Or some other distinctive pattern. Apply that texture to the model, and see how it looks — the landmarks in the texture will guide you where to paint.
Export the model
Create a dummy ARSCNFaceGeometry using the init(blendShapes:) initializer and an empty blendShapes dictionary (you don’t need an active ARFaceTracking session for this, but you do need an iPhone X). Use SceneKit’s scene export APIs (or Model I/O) to write that model out to a 3D file of some sort (.scn, which you can process further on the Mac, or something like .obj).
Import that file into your favorite 3D modeling tool (Blender, Maya, etc) and use that tool to paint a texture. Then use that texture in your app with real faces.
Actually, the above is sort of an oversimplification, even though it’s the simple answer for common cases. ARSCNFaceGeometry can actually contain up to four submeshes if you create it with the init(device:fillMesh:) initializer. But even then, those parts aren’t semantically labeled areas of the face — they’re the holes in the regular face model, flat fill-ins for the places where eyes and mouth show through.
Related
I'm struggling with a texture-baking process with 3DSmax software. I have a white 3D mesh with 2 image textures. I'm trying to get a diffusemap (see target_diffuse_map.jpg). To do this, I exectue the following steps:
1) Affect image-texture1 and image-texture2 to face1 and face2 of the objet.
2) Clone the object to get the white colors when baking texture.
3) unwrap UVM.
4) Rendering Texture to obtain the diffuse map.
5) Projection of the texture + white colors on the cloned object.
Please, find these steps on this small video I made: https://drive.google.com/file/d/1h4v2CrL8OCLwdeVtLmpQwD250cawgJpi/view
I obtain a bad sampled and weird diffuse map (please see obtained_diffuse_map.jpg). What I want is target_diffuse_map.jpg.
I'm I forgetting some steps?
Thank you for your help.
You need to either:
Add a small amount of "Push" in the Projection Modifier
Uncheck "Use Cage" in the Projection Options dialog, while setting a very small value for the offset
Projection Mapping works by casting rays from points on the cage towards corresponding model points on your mesh. You did not push the cage out at all, therefore rays are not well defined; rays are cast from a point toward a direction which is the exact same point. This causes numerical errors and z-fighting. The there needs to be some time amount of push so the "from" and "to" points of each ray are different giving them a well-defined direction to travel.
The second option, instead of using the cage defined in the projection modifier, is to use the offset method (you probably still need to apply projection modifier though). This method defines each rays as starting from a point defined by taking the model point of the mesh and moving outward by a fixed offset amount in the direction of the normal. The advantage is that for curved objects with large polygons, it produces less distortion because the system uses the smoothed shading normal at each point. The disadvantage you can't have different cage distances at different points of the model, for better control. Use this method for round wooden barrels and other simplistic objects with large, smooth curves.
Also, your situation is made difficult by having different parts of the model very close to each other (touching) and embedded within each other - namely how the mouth of the bottle is inside the cap and the cap it touching the base. For this case, it might make sense to break the objects apart after you have the overall UV mapping, run projection mapping separately on each one separately, and then combine the maps back together in an image editor.
I’m interested in the issue of data processing from TrueDepth Camera. It is necessary to obtain the data of a person’s face, build a 3D model of the face and save this model in an .obj file.
Since in the 3D model needed presence of the person’s eyes and teeth, then ARKit / SceneKit is not suitable, because ARKit / SceneKit do not fill these areas with data.
But with the help of the SceneKit.ModelIO library, I managed to export ARSCNView.scene (type SCNScene) in the .obj format.
I tried to take this project as a basis:
https://developer.apple.com/documentation/avfoundation/cameras_and_media_capture/streaming_depth_data_from_the_truedepth_camera
In this project, working with TrueDepth Camera is done using Metal, but if I'm not mistaken, MTKView, rendered using Metal, is not a 3D model and cannot be exported as .obj.
Please tell me if there is a way to export MTKView to SCNScene or directly to .obj?
If there is no such method, then how to make a 3D model from AVDepthData?
Thanks.
It's possible to make a 3D model from AVDepthData, but that probably isn't what you want. One depth buffer is just that — a 2D array of pixel distance-from-camera values. So the only "model" you're getting from that isn't very 3D; it's just a height map. That means you can't look at it from the side and see contours that you couldn't have seen from the front. (The "Using Depth Data" sample code attached to the WWDC 2017 talk on depth photography shows an example of this.)
If you want more of a truly-3D "model", akin to what ARKit offers, you need to be doing the work that ARKit does — using multiple color and depth frames over time, along with a machine learning system trained to understand human faces (and hardware optimized for running that system quickly). You might not find doing that yourself to be a viable option...
It is possible to get an exportable model out of ARKit using Model I/O. The outline of the code you'd need goes something like this:
Get ARFaceGeometry from a face tracking session.
Create MDLMeshBuffers from the face geometry's vertices, textureCoordinates, and triangleIndices arrays. (Apple notes the texture coordinate and triangle index arrays never change, so you only need to create those once — vertices you have to update every time you get a new frame.)
Create a MDLSubmesh from the index buffer, and a MDLMesh from the submesh plus vertex and texture coordinate buffers. (Optionally, use MDLMesh functions to generate a vertex normals buffer after creating the mesh.)
Create an empty MDLAsset and add the mesh to it.
Export the MDLAsset to a URL (providing a URL with the .obj file extension so that it infers the format you want to export).
That sequence doesn't require SceneKit (or Metal, or any ability to display the mesh) at all, which might prove useful depending on your need. If you do want to involve SceneKit and Metal you can probably skip a few steps:
Create ARSCNFaceGeometry on your Metal device and pass it an ARFaceGeometry from a face tracking session.
Use MDLMesh(scnGeometry:) to get a Model I/O representation of that geometry, then follow steps 4-5 above to export it to an .obj file.
Any way you slice it, though... if it's a strong requirement to model eyes and teeth, none of the Apple-provided options will help you because none of them do that. So, some food for thought:
Consider whether that's a strong requirement?
Replicate all of Apple's work to do your own face-model inference from color + depth image sequences?
Cheat on eye modeling using spheres centered according to the leftEyeTransform/rightEyeTransform reported by ARKit?
Cheat on teeth modeling using a pre-made model of teeth, composed with the ARKit-provided face geometry for display? (Articulate your inner-jaw model with a single open-shut joint and use ARKit's blendShapes[.jawOpen] to animate it alongside the face.)
I want to create an Animoji in my APP. But when I contact with some designers they didn't know how to design an Animoji 3D model. Where can I find a solution for reference?
Solution I can thought is create many bones on face of 3D model, And when I get blendShapes of ARFaceAnchor, which contain the detail information of face expression, then I use it to update bone animations of partial face.
Thank you for reading. Any advises is appreciated.
First, to clear the air a bit: Animoji is a product built on top of ARKit, not in any way a feature of ARKit itself. There's no simple path to "build a model in this format and it 'just works' in (or like) Animoji".
That said, there are multiple ways to use the face expression data vended by ARKit to perform 3D animation, so how you do it depends more on what you and your artist are comfortable with. And remember, for any of these you can use as many or as few of the blend shapes as you like, depending on how realistic you want the animation to be.
Skeletal animation
As you suggested, create bones corresponding to each of the blend shapes you're interested in, along with a mapping of blend shape values to bone positions. For example, you'll want to define two positions for the bone for the browOuterUpLeft parameter such that one of them corresponds to a value of 0.0 and another to a value of 1.0 and you can modulate its transform anywhere between those states. (And set up the bone influences in the mesh such that moving it between those two positions creates an effect similar to the reference design when applied to your model.)
Morph target animation
Define multiple, topologically equivalent meshes, one for each blend shape parameter you're interested in. Each one should represent the target state of your character for when that blend shape's weight is 1.0 and all other blend shapes are at 0.0.
Then, at render time, set each vertex position to the weighted average of the same vertex's position in all blend shape targets. Pseudocode:
for vertex in i..<vertexCount {
outPosition = float4(0)
for shape in 0..<blendShapeCount {
outPosition += targetMeshes[shape][vertex] * blendShapeWeights[shape]
}
}
An actual implementation of the above algorithm is more likely to be done in a vertex shader on the GPU, so the for vertex part would be implicit there — you'd just need to feed all your blend shape targets in as vertex attributes. (Or use a compute shader?)
If you're using SceneKit, you can let Apple implement the algorithm for you by feeding your blend shape target meshes to SCNMorpher.
This is where the name "blend shape" comes from, by the way. And rumor has it the built-in ARFaceGeometry is built this way, too.
Simpler and Hybrid approaches
As you can see in Apple's sample code, you can go even simpler — breaking a face into separate pieces (nodes in SceneKit) and setting their positions or transforms based on the blend shape parameters.
You can also combine some of these approaches. For example, a cartoon character could use morph targets for skin deformation around the mouth, but have floating 2D eyebrows that animate simply through setting node positions.
Check-out the 'weboji' javascript library on gitHub. The CG artists we hired to create the 3D models get used with the workflow in minutes. Also, it could be an interesting approach to avoid proprietary formats and closed ecosystem issues.
Screenshots of a 3D Fox (THREE.JS based demo) and a 2D Cartman (SVG based demo).
Demo on youtube featuring a 2D 'Cartman'.
I have an ARKit app that uses plane detection, and successfully places objects on those planes. I want to use some of the information on what's sitting below the object in my approach to shading it - something a bit similar to the WWDC demo where the chameleon blended in with the color of the table. I want to grab the rectangular region of the screen around the footprint of the object, (or in this case, the bounding volume of the whole node would work just as well) so I can take the camera capture data for the region of interest and use it in the image processing, like a metal sphere that reflects the ground it's sitting on. I'm just not sure what combination of transforms to apply - I've tried various combinations of convertPoint and projectPoint, and I occasionally get the origin, height, or width right, but never all 3. Is there an easy helper method I'm missing? I assume basically what I'm looking for is a way of going from SCNNode -> extent.
Hi I'm using Firemonkey because of it's cross platform capabilities. I want to render a particle system. Now I'm using a TMesh which works well enough to display the particles fast. Each particle is represented in the mesh via a two textured triangles. Using different texture coordinates I can show many different particle types with the same mesh. The problem is, that every particle can have its own transparency/opacity. With my current approach I cannot set the tranparency individually for each triangle (or even vertex). What can I do?
I realized that there are some other properties in TMesh.Data.VertexBuffer, like Diffuse or other sets of textures (TexCoord1-3), but these properties are not used (not even initalized) in TMesh. It also seems not easy to simply change this behavior by inheriting from TMesh. It seems one have to inherit from a lower level control to initialize the VertextBuffer with more properties. Before I try that, I'd like to ask if it would be possible to control the transparency of a triangle with that. E.g. can I set a transparent color (Diffuse) or use a transparent texture (TextCoor1)? Or is there a better way to draw the particles in Firemonkey.
I admit that I don't know much about that particular framework, but you shouldn't be able to change transparency via vertex points in a 3D model. The points are usually x,y,z coordinates. Now, the vertex points would have an effect on how the sprites are lighted if you are using a lighting system. You can also use the vertex information to apply different transparency effects
Now, there's probably a dozen different ways to do this. Usually you have a texture with different degrees of alpha values that can be set at runtime. Graphics APIs usually have some filtering function that can quickly apply values to sprites/textures, and a good one will use your graphics chip if available.
If you can use an effect, it's usually better since the nuclear way is to make a bunch of different copies of a sprite and then apply effects to them individually. If you are using Gouraud Shading, then it gets easier since Gouraud uses code to fill in texture information.
Now, are you using light particles? Some graphics APIs actually have code that makes light particles.
Edit: I just remembered Vertex Shaders, which could.