Overview

Depth Locator creates depth-controlled empties on the ray between your camera and any target object. It uses Blender's scripted drivers to position empties along this ray at any distance you specify.

What Problem Does It Solve?

When working with VFX, camera matching, or layout, you often need to place objects at specific depths relative to your camera and a target. Depth Locator makes this fast and intuitive.

Common use cases:

• Quick VFX reference positioning
• Focal length and lens testing
• Depth validation and camera/object relationship testing
• Animation reference and keyframing
• Scene layout and composition planning

System Requirements

• Blender: 3.6.0 or higher (3.6, 3.7, 4.0, 4.1, 4.2, 5.0, 5.1+)
• Python: 3.10+ (built-in with Blender)
• OS: Windows, macOS, Linux
• Disk Space: < 50 KB
• GPU: None required

Quick Start

Get up and running in 5 minutes.

Step 1: Open the Panel

Press N in the 3D Viewport to open the sidebar. Look for the "Depth Locator" tab on the right.

Step 2: Set Up Your Scene

You need:

• A camera (set as the active scene camera)
• A target object (any mesh, empty, light, etc.)

Make sure your camera is set in Scene Properties > Camera.

Step 3: Create a Locator

1. Select the target object you want to measure to
2. Make sure your camera is set as active
3. Click the "Create Depth Locator" button in the panel

An empty will appear on the ray from your camera to the target.

Step 4: Adjust Depth

Use the "Depth" slider in the panel to move the empty along the ray:

• Left (0): At the camera position
• Middle: Halfway to the target
• Right (500+): Beyond the target

The empty updates in real-time as you adjust.

How It Works

The Formula

Depth Locator calculates position using this formula:

world_position = camera_position + normalize(target_position - camera_position) × depth

Breaking it down:

1. camera_position — Where the camera is in 3D space
2. target_position — Where the target object is
3. normalize(...) — Creates a unit direction vector
4. × depth — Scales along that direction by the depth value

Implementation

The addon uses Blender's scripted drivers on the empty's location:

• Three drivers (one for X, Y, Z)
• Each evaluates the position formula every frame
• Updates automatically when camera or target moves
• Keyframeable for animation

Why Pure Drivers?

Instead of constraints, Depth Locator uses drivers because:

Usage Guide

Creating Locators

Basic Creation

1. Select your target object
2. Ensure camera is active scene camera
3. Click "Create Depth Locator" in the panel
4. Adjust the Depth slider

Creating Multiple Locators

You can create as many as needed

Depth_Locator (first)

Depth_Locator.001 (second)

Depth_Locator.002 (third)

... etc

Each is independent and has its own Depth property.

For Different Cameras

If you have multiple cameras:

1. Set Camera A as active scene camera
2. Create locators (they use Camera A)
3. Set Camera B as active scene camera
4. Create new locators (they use Camera B)
5. Switch between cameras to see different locators

Adjusting Depth

Using the Slider

Find the Depth_Locator in the panel and use the slider:

• Soft range: 0 to 500 scene units
• You can exceed this range by typing directly

Using Numeric Input

Click on the depth value and type directly:

• Negative values place the locator behind the camera
• Large values extend far beyond the target
• Decimal values for precise positioning

Real-Time Updates

As you adjust depth:

• The empty moves immediately
• Camera/target movement updates automatically
• All locators update in real-time

Selecting Locators

Find them in the Outliner under "Depth_Locators" collection:

1. Expand "Depth_Locators" in the outliner
2. Click the locator you want to select
3. Its Depth property appears in the panel

Deleting Locators

Delete Individual:

1. Select the locator
2. Press X → Confirm Delete

Delete All:

1. Right-click "Depth_Locators" collection
2. Delete Collection

Advanced Features

Animating Depth

Create motion along the camera ray:

1. Select Depth_Locator object
2. Frame 1: Set depth to 0, right-click Depth property → "Insert Keyframe"
3. Frame 100: Set depth to 500, right-click → "Insert Keyframe"
4. Play animation to see smooth motion

Using with VFX

Position reference points for effects:

1. Create locators at key distances
2. Use them as guides for effect placement
3. Animate depth to match character movement
4. Delete after you're done with reference

Combining with Other Tools

With Constraints:

• Create locators first
• Use them as targets for other objects
• Constrain cameras/lights to locators

With Drivers:

• Link depth to other properties
• Create complex relationships
• Automate scene setup

With Animation:

• Keyframe depth for smooth motion
• Create depth-based motion graphics
• Animate multiple locators together