I'm building a 3D app that uses SceneKit. My scene will have various 3D objects and a moveable perspective camera.
The user can load a 2D image into the scene, which I will display on a 3D plane using the image as the material.
What I need to be able to do is to initially show the image as if it were actually 2D, where the pixel width and height are the same as the image and it is not distorted by the camera perspective. So basically I need to know how to position that plane in relation to the camera to make it look 2D.
Thanks in advance for any tips :)
It's not clear where you are getting stuck.
If you're just looking for where to start, look at SCNPlane and SCNBillboardConstraint.
I do not know SceneKit, so what I suggest might not be doable in the specific program, but could you perhaps use an orthographic camera perspective? It removes a lot of the visual depth from a scene, combining that with some flat lighting might accomplish the look you are going for.
Related
I'm developing an application that uses SceneKit API and I faced the problem that I basically cannot apply a texture to a sphere object and keep texture's pre-defined size. I'm able to either scale the texture up to the object's surface (default SceneKit's behavior) or repeat it. But what I want to achieve is similar to the billiard ball:
Let's say I have a a .png image of a white circle with the number "13" at the center of it. I want to put it like the one on the picture. Generally, I want it to be scaled up to a fixed size, not the whole surface.
I use material.diffuse.contents property of SCNGeometry to set the texture and I found contentsTransform property in the documentation which can probably help me sort it out but I didn't find an explanation how to use it with the sphere object.
Is it something that is possible with pure SceneKit? Any help would be very appreciated.
You need a preliminarily modelled geometry (polygonal sphere in your case) and its UV Mapped texture that's made in 3D modelling software (Autodesk Maya for instance).
Watch this short movie to find out how to get UV-mapped texture.
Thanks in advance for reading my question. I am really new to ARKit and have followed several tutorials which showed me how to use plane detection and using different textures for the planes. The feature is really amazing but here is my question. Would it be possible for the player to place the plane all over the desired area first and then interact with the new ground? For example, could I use the plane detection to detect and put grass texture over an area and then drive a real RC car over it? Just like driving it on real grass.
I have tried out the plane detection on my iPhone 6s while what I found is when I tried to put anything from real world on the top of plane surface it just simply got covered by the plane. Could you please give me some clue if it is possible to make the plane just stay on the ground without covering the real world object?
I think that's sth what you are searching for:
ARKit hide objects behind walls
Or another way is i think to track the position of the real world object for example with apples turicreate or CoreML or both -> then don't draw your stuff on the affected position.
Tracking moving objects is not supported, that's actually what it would be needed to make a real object interact with the a virtual one.
Said that I would recommend you using 2D image recognition and "read" every camera frame to detect the object while moving in the camera's view space. Look for the AVCaptureVideoDataOutputSampleBufferDelegate protocol in Apple's developer site
Share your code and I could help with some ideas
Hello i can't for the life of me work out how to add a 2D image in the scene using scenekit is it even possible? What I'm trying to accomplish is have a 3D flying plane over a 2D background image but the background image can't cover the whole screen. Thanks to anyone that can help
Others have said plenty good suggestions above.
Let me summarize each solution with different scenarios:
Using scnScene.background: Easiest, but fullscreen and static. You cannot display in a smaller area of the scene, nor can you customize the transformations.
Using scnScene.overlaySKScene to display a 2D SKScene and adding image sprite. This is probably what fits your scenario. If you want static but with configurable transformations, this is a good choice. Notably overlaySKScene is recommended by Apple to create HUD in your 3D scene.
However, if you want the 2D content to track the 3D movement, you need to do some coordinate conversion from 3D space to 2D space every frame. Bad news is the job is done by CPU, which will add performance drag. (Believe me, this frustrate me too!)
Using SCNNode with SCNPlane geometry and set the diffuse.content with the image; add SCNBillBoardConstraint to the node to ensure it's always facing the camera.
Most flexible. However if your camera is not orthographic, the picture is going to zoom as the fov of camera changes, which doesn't look 2D but rather a hanging 3D billboard.
SceneKit and SpriteKit play very nicely together.
Implement the background 2D image as a SceneKit node with SCNPlane geometry, using your image as the plane's material. If you want to get fancier, use a full, live SpriteKit scene as the SCNPlane's material. Place that node at the far end of your camera's frustum, with your 3D aircraft in front of it.
You might also consider providing a cube map (skybox) as your scene's background. See SCNScene.background.
You can use the background property on SCNScene to set a background image.
scnScene.background.contents = UIImage(named: "myImage")
Contents
You can set a value for this property using any of the following
types:
A color (NSColor/UIColor or CGColorRef), specifying a constant color
across the material’s surface
An image (NSImage/UIImage or CGImageRef), specifying a texture to be
mapped across the material’s surface
An NSString or NSURL object specifying the location of an image file
An array of six images (NSArray), specifying the faces of a cube map
A Core Animation layer (CALayer)
A texture (SKTexture, MDLTexture, MTLTexture, or GLKTextureInfo)
A Sprite Kit scene (SKScene)
I want to make a plan which cover 360angle, and my device camera remain inside of this 360 angle plan. I can also able to show some textures on it. When user move camera toward right then plan should move toward left and vice versa. Actually what I want to achieve I am making Geocaching app in Unity. I will have to show 2d and 3d objects with help of compass. So how can i achieve this in unity, if someone have any idea lets share with me. Thanks in advance?
You will need to flip the direction of the face normals of your cylinder to make the texture appearing from inside the cylinder. Have a look at this Blender model to get an idea. In Blender (the only modelling software I know) you have to select all faces in edit mode and then click Flip Direction in tool shelf. Then you can proceed with UV mapping as usual.
I have an image on the wall. I'd like to create its 3D perspective views by myself. Suppose the points on the images, camera location, orientation of the camera are given, how can I do to obtain the 3d perspective matrix to play with the original image?
I understand I can use the orientation of the camera to calculate the 3d rotation matrix, but I've no idea how to calculate the subsequent projection matrix...
I've come across this link (see Section Perspective Projection), but I don't understand what's going on after projection.. And what is the difference between the camera position and the viewer's position?
Thanks a lot.
use openGl and its open example to solve your problem.
in bellow link there are good samples to undestand 3d reconstruction:
http://www.songho.ca/opengl/gl_transform.html
wish helpful