colmap · B1ueber2y · Jun 12, 2025 · Jun 11, 2025 · Jun 11, 2025 · Jun 11, 2025
diff --git a/doc/concepts.rst b/doc/concepts.rst
@@ -0,0 +1,66 @@
+.. _concepts:
+
+Key Concepts
+============
+
+Starting from COLMAP 3.12, the concepts of rigs and frames have been introduced
+to enable a principled modeling of multi-sensor platforms as well as 360° panorama
+images. These concepts provide a structured framework to organize sensors and
+their measurements, enabling more flexible calibration and fusion of diverse
+data types (e.g., see :ref:`rig-support`).
+
+These additions are backward-compatible and do not affect the traditional, default usage
+of COLMAP for single-camera capture setups.
+
+
+.. _sensors:
+
+Sensors and Measurements
+------------------------
+
+A **sensor** is a device that captures data about the environment, producing
+measurements at specific timestamps. The most common sensor type is the camera,
+which captures images as its measurements. Other examples include IMUs
+(Inertial Measurement Units), which record acceleration and angular velocity,
+and GNSS receivers, which provide absolute position data. 
+
+Currently, COLMAP supports only cameras and their image measurements, though the
+sensor concept is designed to extend to other types such as IMUs and GNSS for
+future support of multi-modal data fusion.
+
+
+.. _rigs:
+
+Rigs
+----
+
+A **rig** models a platform composed of multiple sensors with fixed relative poses,
+enabling synchronized and consistent multi-sensor data collection. Examples
+include stereo camera setups, headworn AR/VR devices, and autonomous driving
+sensor suites. It can also be virtual — for example, a rig modeling multiple
+virtual cameras arranged to capture overlapping views used to create seamless
+360° panoramic images.
+
+In COLMAP, each sensor must be uniquely associated with exactly one rig. Each rig
+has a single reference sensor that defines its origin. For example, in a stereo
+camera rig, one camera is designated as the reference sensor with an identity
+`sensor_from_rig` pose, while the second camera’s pose is defined relative to
+this reference. In a single-camera setup, the camera itself serves as the sole
+reference sensor for its rig.
+
+
+.. _frames:
+
+Frames
+------
+
+A **frame** represents a rig captured at a single timestamp, containing measurements
+from one or more sensors within that rig. For example, if a rig consists of
+three sensors, a frame may include measurements from all three sensors, or only
+a subset, depending on availability. This concept allows association of multi-sensor 
+data at specific points in time.
+
+For instance, in a stereo camera rig recording video, each frame corresponds to a
+set of two images—one from each camera—captured at the same moment.
+
+
diff --git a/doc/conf.py b/doc/conf.py
@@ -47,7 +47,7 @@
 
 # General information about the project.
 project = "COLMAP"
-copyright = "2024, Johannes L. Schoenberger"
+copyright = "2025, Johannes L. Schoenberger"
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the

diff --git a/doc/database.rst b/doc/database.rst
@@ -28,7 +28,7 @@ Rigs and Sensors
 
 The relation between rigs and sensors (cameras, etc.) is 1-to-N with one sensor
 being chosen as the reference sensor to define the origin of the rig. Each sensor
-must only be be part of one rig.
+must only be part of one rig.
 
 
 Rigs and Frames

diff --git a/doc/index.rst b/doc/index.rst
@@ -105,6 +105,7 @@ support (special credits to `Torsten Sattler <https://tsattler.github.io>`_).
 
    install
    tutorial
+   concepts
    database
    cameras
    rigs
-Original file line number
+Diff line change
@@ Expand Up @@
        install
        tutorial
+       concepts
        database
        cameras
        rigs
@@ Expand Down @@