> For the complete documentation index, see [llms.txt](https://beyond-3.gitbook.io/beyond-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://beyond-3.gitbook.io/beyond-docs/blender-addons/readme/how-to-use-forced-perspective.md). # How to Use Forced Perspective {% stepper %} {% step %} ### Choose the view source Open Select Camera in the main CamKeys panel. New setups start in Viewport. Choose Camera and select the scene camera when you want its motion to drive the shot or when you plan to bake. * Camera vs. Viewport: Use the toggle buttons to switch between using a selected camera and using the viewport’s perspective. Important: The Baking Function will only work when “Camera” is selected.
Choose Viewport to drive live effects from your view without a shot camera.

Choose Viewport to drive live effects from your view without a shot camera.

Choose Camera and select your shot camera. Lock Cam to View lets viewport navigation move it; the button reads Unlock Cam from View while locked.

Choose Camera and select your shot camera. Lock Cam to View lets viewport navigation move it; the button reads Unlock Cam from View while locked.

* Lock/Unlock Camera to View: If you’re using the camera (and not the viewport), you can lock or unlock the camera so that it follows your viewport movement. {% endstep %} {% step %} ### Tracked Objects Choose the object whose perspective you want to control. Add other affected objects from the linked-object list in Forced Perspective.
Use + in Tracked Objects to add the subject. Select its row before editing its links.

Use + in Tracked Objects to add the subject. Select its row before editing its links.

* Adding Mesh Objects: Click the + button to add an object to the tracking list. If the object is rigged, you can optionally select a bone (using the provided dropdown) for more precise control. * Managing the List: Each object appears in a list where you can enable or disable it individually, move its position in the list, or remove it. {% endstep %} {% step %} ### Forced Perspective Panel Select the tracked subject. Lens changes its apparent optics; Subject Size gives you direct control over the front, subject and back of the pose from the active view.
Choose Forced Perspective to compare Lens and Subject Size in the setup wizard.

Choose Forced Perspective to compare Lens and Subject Size in the setup wizard.

{% stepper %} {% step %} ### Enable the effect Open Forced Perspective and click Enable Forced Perspective for the selected subject. Effect Strength blends from the incoming mesh at 0% to your chosen correction at 100%. You can compare the two without losing your lens or plane settings.
Click Enable Forced Perspective. The button changes to Disable Forced Perspective while the effect is active.

Click Enable Forced Perspective. The button changes to Disable Forced Perspective while the effect is active.

{% endstep %} {% step %} ### Set the FOV focus subject Under FOV Focus Subject choose an object, bone, vertex group, material, or vertex color. For a punch toward the viewer, choose the face or head as your reference so the fist can sit in front of it. Other Objects to Correct lets separate hair, clothing and props share the same reference.


Choose the focus type under FOV Focus Subject. With Use a Bone selected, set the armature and focus bone.

{% hint style="info" %} The tracked object supplies the default object reference. For an animated character, choose its armature and a focus bone to make the correction follow that pose. {% endhint %} {% endstep %} {% step %} ### Lens: change the apparent focal length Keep the camera still and change Apparent Focal Length. Below the real lens, nearby features loom larger. Above it, near and far features read more alike. CamKeys redistributes geometry around the focus and tries to preserve its overall volume, instead of simply flattening the mesh in depth. Volume is an overall target, not a guarantee for each detail. Open meshes, partial strength, masks, and local compression near the camera can change volume or thickness. Inspect the silhouette from your shot camera and from the side before committing the pose.
Same mesh and fixed 50 mm camera throughout. Watch the snout and ears as the apparent lens changes, then watch the 220 mm correction fade to zero.

Same mesh and fixed 50 mm camera throughout. Watch the snout and ears as the apparent lens changes, then watch the 220 mm correction fade to zero.

{% endstep %} {% step %} ### Use a short apparent lens New setups start unlocked. Drag Apparent Focal Length below the real camera or viewport lens for a wide-angle look. If an older setup stops at the real lens, open its padlock. Reset beside the slider matches the current source lens. Very short apparent lenses can clip nearby geometry.
Choose Lens. The padlock beside Apparent Focal Length controls whether you can go below the source lens.

Choose Lens. The padlock beside Apparent Focal Length controls whether you can go below the source lens.

{% endstep %} {% step %} ### Subject Size: pose in three depth layers Choose Subject Size in the setup wizard or beside Lens in Forced Perspective. Think of the controls like three layers in a 2D drawing: the Front View Plane is closer to the viewer than the focus region, the Subject View Plane spans that region, and the Back View Plane is farther away. These are depth ranges in the current view; you do not assign objects to layers. {% embed url="" %} Watch the fist, face and trailing leg as the view-plane settings change. The second viewport shows the same character from another angle. {% endembed %} To push a punch, keep Subject Size at 1× so the face stays your reference. Raise Front Size to bring the fist forward visually, then reduce Back Size to tuck the trailing leg away. New settings start at Front 2.25×, Subject 1× and Back 0.725×. Each plane has its own Size; none moves the camera.
Use Size and View offset in the plane you want to change. The front and back cards also have a Transition width and curve.

Use Size and View offset in the plane you want to change. The front and back cards also have a Transition width and curve.

Drag a plane’s View offset pad, or enter X and Y to shift its silhouette sideways or vertically. Offsets follow the view and are measured in subject depths. Move the front fist clear of the face, then offset the back foot in the other direction to open the silhouette. Front and Back each have a Transition width in subject depths. Increase it to spread the change over more depth; use the adjacent curve to shape that blend. Reset beside a plane restores 1× and zero offset; reset beside Subject Size does this for all three. Neither reset changes your transition widths or curves. Switch back to Lens to use lens-based shaping. {% endstep %} {% step %} ### **Add multiple objects** Use Other Objects to Correct for clothing, hair or accessories that should follow the same correction. Use + for one object or one of the batch buttons for an armature, related objects or the current selection.
Use + under Other Objects to Correct for a companion, or use a batch button for the selected objects or armature.

Use + under Other Objects to Correct for a companion, or use a batch button for the selected objects or armature.

{% embed url="" %} Apply a custom apparent focal length to each object. [Original demo on X](https://x.com/realBeyondDev/status/1996601076406006166?s=20) {% endembed %} {% endstep %} {% step %} ### **Adjust Forced Perspective Falloff** In Lens mode, the curve beside Apparent Focal Length opens separate Long Lens and Short Lens responses. Distance Falloff uses Near Dist and Far Dist; Multi-Object Falloff controls how far correction reaches other objects. Open the curve beside the setting you mean to change. A preset shows its curve immediately; editing its points switches to Custom. Front/Back Transition in Subject Size is a separate control.
The upper curve button edits lens response. The curve beside Near Dist and Far Dist edits the distance fade.

The upper curve button edits lens response. The curve beside Near Dist and Far Dist edits the distance fade.

Character example: watch the silhouette as the falloff changes.

Character example: watch the silhouette as the falloff changes.

In Long Lens, Front falloff distance and Back falloff distance set how far beyond the respective focus bounds the curve reaches its endpoint. Zero uses the automatic range. If an extended hand and forearm both seem stuck at the end of your curve, increase Front falloff distance, then adjust the curve. The distances use the posed mesh before Forced Perspective. For Beyond VTuber Tools shadow rendering, leave Animated Source Shadows enabled to use the animated surface before CamKeys deforms or steps it. Ordinary Blender lighting and other renderers need not use that shadow reference. {% endstep %} {% endstepper %} {% endstep %} {% step %} ### Camera Effect Locks Open **Camera Effect Locks** below **FOV Focus Subject**. Each lock captures the current camera/view and focus when you enable it. Choose the focus first, frame your subject, then click the lock beside the effect.
Frame the subject and click the padlock beside the effect you want to capture.

Frame the subject and click the padlock beside the effect you want to capture.

{% hint style="info" %} **Use Blender’s native middle-mouse navigation!** In perspective Viewport mode, Ctrl + MMB drag dolly/zooms, MMB orbits, and Shift + MMB pans with Blender’s default keymap. The camera locks update during the movement. Mouse-wheel zoom and supported trackpad navigation work too; custom keymaps retain their native navigation bindings. {% endhint %} In **Camera** mode, use **Lock Camera to View** if you want viewport navigation to move the camera itself. Resizing the camera border without moving the camera is only a viewport display change. You can also move or animate the camera normally. * **Dolly Zoom** responds to movement toward or away from the captured focus by adjusting the real lens. * **Pincushion → View Motion** adds inward bowing as you move closer to the captured focus. * **Tangential → View Motion** responds to lateral movement and changes of viewing direction, such as pan and orbit. Unlock an effect to release it. Lock it again to capture a new starting view. Captures are saved with the file. Change the focus selection before relocking if you want to use a different reference. {% hint style="info" %} Camera effect locks need **perspective projection**. Switching the camera, view source, or captured viewport can suspend a lock. Read the message next to it, return to the captured source, or unlock and relock. {% endhint %} {% stepper %} {% step %} ### Dolly Zoom Dolly Zoom keeps the captured focus plane at a consistent apparent size while perspective and the background change. Moving closer widens the real camera/view lens; moving farther away lengthens it. A deep subject can still change silhouette because its parts are at different depths. In Run Setup… choose Dolly Zoom + Camera Tricks. Set the starting lens; use Snap to Front View if you want a new framing, or Dolly at Current View to capture without moving. The lens is controlled while locked. Unlink Dolly restores the captured lens and distance when CamKeys still owns them. Back keeps a prepared effect; use Undo to revert its creation. * Enable **Forced Perspective**, choose **FOV Focus Subject**, then lock **Dolly Zoom**. * Use **Ctrl + MMB drag** in the perspective viewport to move in and out, or animate the camera. CamKeys adjusts the lens automatically during the native navigation. * Use the displayed **Lens** value to see the active camera or viewport focal length. Keep **Apparent Focal Length** matched to it for a purely optical example, or use Forced Perspective/lens stops to style the subject separately. {% embed url="" %} Dolly Zoom + depth of field (first 8 seconds), followed by a Forced Perspective sweep (last 4 seconds). Red: OFF. Green: ON. The final sweep changes apparent focal length while the real camera stays fixed. {% endembed %} The focus blur in this example is Blender’s camera **Depth of Field**. Set that separately in Camera properties; the Dolly lock controls the lens, not a focus-distance animation. {% hint style="info" %} One actor controls a lens at a time. A keyed, driven, linked, or already-owned lens can suspend Dolly rather than overwrite its animation. Dolly also respects lens limits and the near plane. Reverse your movement to come back into range. {% endhint %} Unlocking restores the captured lens and depth when CamKeys still owns them, while preserving orbit and lateral pan. Temporarily disabling the effect releases control; re-enabling reuses its capture. {% stepper %} {% step %} ### Lens Compensation Stops
The first button after the Dolly lens opens its compensation stops.

The first button after the Dolly lens opens its compensation stops.

Use lens stops when a character needs different **Apparent Focal Length** settings at wide and long real lenses. These stops control the geometry correction; they do not redefine Dolly Zoom’s captured lens or distance.
Enable Use Lens Stops, then add stops at the real lens values you want to style.

Enable Use Lens Stops, then add stops at the real lens values you want to style.

* Open the first accessory button after the Dolly Lens value, immediately before the expression button. * Enable **Use Lens Stops**. This records the current lens and apparent focal length as the first stop. * Move to another real camera or viewport lens and press + to author its stop. Enable Auto Add Stops if direct Apparent Focal Length edits should create or update stops. With automatic recording off, a manual edit returns control to the slider. * Values blend linearly between lens stops and hold the nearest end value outside the range. Disable **Use Lens Stops** to return to the ordinary Apparent Focal Length setting. Lens stops also work without the Dolly lock. The reset control beside Apparent Focal Length matches the current camera/viewport lens. Turn on Keep Stops on Unlock before releasing a Dolly lock if you want to retain its stops. Both automatic recording and retention start off. {% endstep %} {% step %} ### Dolly Expressions and Shape Keys {% embed url="" %} Dolly Zoom driving character expressions and shape keys. {% endembed %} Open the **shape-key icon** beside the Dolly **Lens** field to blend expressions as the lens changes. This is useful for a subtle facial correction that grows stronger in a wide-angle shot.
Use the second button after the Dolly lens to open expressions and shape keys.

Use the second button after the Dolly lens to open expressions and shape keys.

Choose Shape Keys or VRM Expression, add targets, then capture the FOV with ON.

Choose Shape Keys or VRM Expression, add targets, then capture the FOV with ON.

* Choose **Shape Keys** or **VRM Expression**, add the desired targets, and set an independent weight for each row. * Press **ON** to capture the current vertical field of view. **FOV Change** defines how far the view must change to reach full influence: positive values go toward a wider view, negative values toward a narrower view. * A +60° range goes from zero at the capture to full influence 60° wider, limited by the available lens range. **OFF** releases the link and restores values that CamKeys still owns. {% hint style="info" %} VRM expressions require the VRM add-on and a mapped rig. Ordinary relative shape keys work without VRM. Avoid assigning the same target to multiple procedural expression tools; keyed or driver-controlled channels are not taken over. {% endhint %} {% endstep %} {% endstepper %} {% endstep %} {% step %} ### Pincushion Pincushion bends the selected geometry inward at the sides of the image. Enable its lock at the view you want to use as the reference. * **View Motion:** neutral at capture; use native **Ctrl + MMB zoom** or move the camera closer to increase the effect. Returning to the reference depth returns it to neutral. Moving farther away does not reverse it into barrel distortion. * **Constant:** keeps the chosen strength while following the current projection. * **Strength:** controls how pronounced the deformation is. {% embed url="" %} Pincushion OFF/ON with the same approach-and-return camera motion and a fixed 34 mm lens. The cream frame makes the inward curve visible. {% endembed %} {% endstep %} {% step %} ### Tangential Tangential adds a directional warp to the selected geometry. Lock it at your neutral view, then pan or orbit using Blender’s native middle-mouse controls. * **View Motion:** responds to lateral camera motion and viewing-direction changes. Return to the captured view to return to neutral. * **Constant:** applies a steady directional warp. * **Direction:** rotates the response. **Strength** sets its amount. * **Keep Focus Anchored:** removes this effect’s displacement at the focus point. Normal camera panning still moves the image, and other effects can still affect it. {% embed url="" %} Tangential OFF/ON with identical orbit-and-return camera motion and a fixed 34 mm lens. The effect follows viewing direction without changing the lens. {% endembed %} {% endstep %} {% step %} ### Masks, Geometry and Linked Objects Pincushion and Tangential deform geometry inside Forced Perspective. They affect shadows, reflections and surface relationships, so use them as modeling/animation effects rather than expecting a pixel-identical compositor lens filter. * Use the existing linked-object list to carry the projection across a character’s separate parts. Lattice targets forward the effect to their consumers. * **Effect Mask** uses a vertex-group name shared across affected objects. A missing group means full influence. The mask affects the geometry warp, not Dolly’s camera lens. * **Extra Subdivision** adds simple mesh subdivision before the warp. Long edges need enough vertices to bend smoothly; increase it only as needed. Curve and hair detail comes from their own geometry setup. {% hint style="info" %} Unchanged inputs do not need repeated geometry-setting writes, but more vertices, subdivision and other modifiers still add evaluation cost. {% endhint %} {% endstep %} {% endstepper %} {% endstep %} {% step %} ### Billboard Emulation **Billboard Emulation** holds a 3D character at stepped viewing angles, giving a multi-billboard look while keeping the model rigged and animated. Enable it in Forced Perspective, then open the **settings cog** at the right of its checkbox.
Enable Billboard Emulation, then click the cog to set up its steps or groups.

Enable Billboard Emulation, then click the cog to set up its steps or groups.

{% embed url="" %} Billboard Emulation: stepped character turnaround. {% endembed %} * The armature is normally found from the mesh or lattice setup. You do not need to select the armature first. **Override Armature** is at the bottom of the popover, behind its disclosure toggle. * **Create Head / Body** uses VRM 0.x or VRM 1.0 humanoid bones as starting values when available. Without a mapping, choose your own **Head Bone** and optional body **Pivot Bone** in the setup dialog. Leave Pivot Bone empty to use the armature origin. * To override existing groups, select **head** and edit **Root Bone**, or select **body** and edit **Pivot Bone**, in the settings popover. These choices affect CamKeys without changing your VRM mapping. * **head** owns its chosen root and descendants, except branches assigned to nested groups. **body** contains all remaining bones; its pivot changes the rotation center, not bone membership. * Enable **Separate Billboards** to configure groups. Select each group in the list to set its own axis toggles and step counts in the same popover. * **Vertical** steps rotation around the character’s upright axis (turnaround/yaw). **Horizontal** steps tilt away from that axis. An unchecked axis stays continuous. Fewer steps produce larger angular jumps. With Separate Billboards off, the object uses a shared set of steps. For grouped billboards, returning to the same angular bin uses the same reference angle regardless of the direction you approached it. {% stepper %} {% step %} ### Billboard Groups and Boundaries * **Split Limbs** uses the VRM humanoid mapping to separate the arm and leg subtrees. Hands/fingers and feet/toes initially remain with their limbs; use **Split Hands** or **Split Feet** to separate them. Without those mappings, use **+** to define the same groups manually with your own root bones. * Use **+** for a custom group, name it, and choose its **Root Bone**. That bone and its children belong to the group. A nested group takes priority over its parent, so a hair root can become a separate **hair** billboard inside the head subtree. * **Assignment** can use automatic bones or an explicit object, material, or vertex group. Use explicit assignments when a model’s weights do not cleanly describe the pieces you want. * **Blended Skin Weights** is the default for new setups and blends group transformations using existing weights. Use it for smoother shared boundaries; the weight painting still determines the transition. * **Rigid Mesh Islands** keeps connected pieces rigid, assigning each island by its dominant group weights. It is useful for separate accessories and detached mesh pieces. * Click **Rebuild Assignments** after changing topology, weights or bone hierarchy. Existing saved rigid setups keep their chosen boundary mode. {% hint style="info" %} Blending smooths the transformation across weights; it does not cut, remesh or seal geometry. For clean rigid seams, author separate pieces or use suitable object/material assignments. {% endhint %} CamKeys and CamProps can share the stepped viewing reference with Billboard Emulation. Distance-only controls remain continuous. Compatible Beyond VTuber Tools versions coordinate head look-at and spring simulation during snap transitions, including when look-at is off; BVT is optional. {% endstep %} {% endstepper %}
Choose Create Head / Body to configure a head root and body pivot. Separate Billboards gives groups their own steps.

Choose Create Head / Body to configure a head root and body pivot. Separate Billboards gives groups their own steps.

{% endstep %} {% endstepper %}