Schematic KDL

Glossary

• Top-level nodes: panel variants, object_3d, line_3d, vector_arrow, window.
• EQL: expressions are evaluated in the runtime EQL context. Vector-like fields expect 3 components; world_pos is a 7-component array (quat + position).
• Colors: color r g b [a] or named (black, white, blue, red, orange, yellow, yalk, pink, cyan, gray, green, mint, turquoise, slate, pumpkin, yolk, peach, reddish, hyperblue); alpha optional. Colors can be inline or in color/colour child nodes. Defaults to white when omitted unless noted.

theme

• Optional top-level node that sets the session UI appearance.
• mode: "dark" (default) or "light"; drives window decorations and picks the dark/light variant of the color scheme. If a preset does not ship a light variant, the theme stays in dark.
• scheme: name of a color preset. Built-ins are default, eggplant, catppuccini-macchiato, catppuccini-mocha, catppuccini-latte, and matrix; user presets are picked up from any color_schemes folder in the asset directory or data directory. Unknown names fall back to default. If a user preset shares a name with a built-in, the user version wins. See color-schemes for the file layout.
• Applies to the whole session; a secondary file can set its own mode for its windows, but the active scheme stays the one from the primary schematic.
• Controls both egui styling (palette) and the window decoration theme (Dark/Light).

window

• path/file/name: optional secondary schematic file. Relative paths resolve against the parent schematic directory (or CWD). If absent, the entry configures the primary window instead of loading a secondary file.
• title/display: optional window title.
• screen: optional zero-based display index.
• rect { x y width height }: optional child; four percentages (clamped 0–100). Used for placement of primary or secondary windows. Secondary windows default to DEFAULT_SECONDARY_RECT when unset.

panel containers

• tabs { ... }: children are panels. No extra props.
• hsplit / vsplit: children are panels. Child share=<f32> controls the weight within the split. active (bool) is parsed but not currently used. Optional name.

panel content

• viewport: fov (default 45.0), optional near/far clipping planes (if omitted, camera defaults are near=0.05 and far=5.0; if set, they are applied to the camera projection), optional aspect (if omitted, ratio is derived from viewport size), active (bool, default false), show_grid (default false), show_arrows (default true), create_frustum (default false; creates that viewport camera frustum), show_frustums (default false; shows frustums created by other viewports on this viewport), frustums_color (default yellow), frustums_thickness (default 0.006 world units), show_view_cube (default true), hdr (default false), name (optional label), camera pos/look_at (optional EQL). Vector arrows can also be declared directly inside the viewport node; those arrows are treated as part of that viewport’s layer and respect its show_arrows/show_grid settings, allowing you to build a local triad tied to the viewport camera. An up (default "(0, 1, 0)") specifies a direction vector in the world frame for the camera.
• graph: positional eql (required), name (optional), type (line/point/bar, default line), lock (default false), auto_y_range (default true), y_min/y_max (default 0.0..1.0), child color nodes (optional list; otherwise palette).
• component_monitor: component_name (required), name (optional).
• action_pane: name (required pane title), lua script (required).
• query_table: name (optional), positional query (defaults to empty), type (eql default, or sql).
• query_plot: name (required pane title), query (required), refresh_interval in ms (default 1000), auto_refresh (default false), color (default white), type (eql default, or sql), mode (timeseries default, or xy for numeric X-axis labels), x_label (optional X-axis label for XY mode), y_label (optional Y-axis label).
• data_overview: name (optional pane title).
• schematic_tree: name (optional pane title). (Hierarchy/Inspector sidebars are implicit and not serialized.)
• video_stream: positional msg_name (required; the message name matching the elodinsink msg-name property), name (optional display label; defaults to "Video Stream <msg_name>"). Displays an H.264 video stream received by Elodin DB. The video source can be a GStreamer pipeline using elodinsink, an OBS Studio SRT stream via a receiver pipeline, or any source that sends H.264 NAL units to Elodin DB. See the OBS Studio Integration section below.
• dashboard: layout node (Bevy UI style). Key properties: name (optional), display (flex default, or grid/block/none), box_sizing (border-box default or content-box), position_type (relative default or absolute), overflow (per-axis; defaults visible), overflow_clip_margin (visual_box + margin, defaults content-box / 0), sizing (left/right/top/bottom/width/height/min_*/max_* accept auto, px, %, vw, vh, vmin, vmax; default auto), aspect_ratio (optional f32), alignment (align_items/justify_items/align_self/justify_self/align_content/justify_content, all default to default variants), flex (flex_direction, flex_wrap, flex_grow default 0, flex_shrink default 1, flex_basis default auto, row_gap/column_gap default auto), children (nested dashboard nodes), colors via bg/background child (default transparent), text (optional), font_size (default 16), text_color child (default white), spacing via margin/padding/border children with left/right/top/bottom.

object_3d

• Positional eql: required. Evaluated to a world_pos-like value to place the mesh.

• Mesh child (required, exactly one):

  • glb: path (required), scale (default 1.0), translate (x,y,z) (default 0s), rotate (deg_x,deg_y,deg_z) in degrees (default 0s).
    • animate child nodes (optional, multiple): For rigged GLB models, animate specific joints/bones.
      • joint: required string; the exact name of the joint/bone in the GLB file.
      • rotation_vector: required EQL expression; must evaluate to a 3-element vector (x, y, z) where:
        • The vector direction is the rotation axis.
        • The vector magnitude is the rotation angle in degrees.
      • Example: animate joint="Root.Fin_0" rotation_vector="(0, rocket.fin_deflect, 0)"
  • sphere: radius (required); color (default white).
  • box: x, y, z (all required); color (default white).
  • cylinder: radius, height (both required); color (default white).
  • plane: width/depth (default size if set, else 10.0); optional size shorthand; color (default white).
  • ellipsoid: , color (default white), show_grid (default #false).
    • Physical measure -scale an EQL string, e.g., "(1, 1, 1)" in meters
    • Error measure
      • error_covariance_cholesky as an alternative to specifying the scale and rotation, one can specify the lower triangle cholesky L of the error covariance matrix P = LL^T. Example "(a,b,c,d,e,f)" which describes a matrix that looks like this: | a 0 0 | | b c 0 | | d e f |
      • error_confidence_interval (default 70) the percentage that if this were repeated 100 times, we would expect that in 70 cases, the true value would be within the bounds. In practice this means that the larger the error confidence interval, the larger the ellipsoid.

  Mesh nodes support an optional emissivity=<value> property (0.0–1.0) to make the material glow (e.g., sphere radius=0.2 emissivity=0.25 { color yellow }).

  Mesh nodes and icon nodes both support an optional visibility_range child node that controls at what camera distances the element is rendered:

  • visibility_range: child node with min (default 0) and max (default infinity) properties. The element is visible when the camera distance is between min and max. Both mesh and icon are visible at all distances by default; visibility_range is purely opt-in.
  • fade_distance (icon only, default 0): world-unit distance over which the icon fades in at the min boundary and fades out at the max boundary. For example, min=50 fade_distance=50 means the icon starts appearing at distance 50 (alpha=0) and reaches full opacity at distance 100. Mesh nodes use hard visibility cutoffs at their min/max boundaries.
  • Ranges can overlap (both mesh and icon visible simultaneously) or have gaps.

• icon child (optional): Displays a fixed-size billboard icon at the object's position. Each viewport camera independently evaluates whether to show the icon based on its own distance. The icon always faces the camera and maintains a constant screen pixel size.

  • Source (exactly one required):
    • builtin: name of a Material Icons glyph (snake_case). Supported names include: satellite_alt, satellite, rocket_launch, rocket, flight, flight_takeoff, public, language, circle, fiber_manual_record, star, star_outline, location_on, place, adjust, gps_fixed, my_location, explore, navigation, near_me, diamond, hexagon, change_history, lens, panorama_fish_eye, radio_button_unchecked, brightness_1, flare, wb_sunny, bolt.
    • path: path to a custom PNG image file (loaded from the assets folder).
  • color child node: tint color for the icon using the standard color r g b [a] format or named colors (default white). See Colors in the glossary above.
  • visibility_range child node: min, max, and fade_distance in world units (see above).
  • size: desired screen pixel size of the icon (default 32).

line_3d

• Positional eql: required; expects 3 values (or 7 where the last 3 are XYZ).
• line_width: default 1.0.
• color: default white.
• perspective: default true (set false for screen-space lines).

vector_arrow

• vector: EQL expression yielding a 3-component vector (required).
• origin: EQL for arrow base; world_pos or 3-tuple (optional).
• scale: numeric multiplier (default 1.0).
• normalize: #true/#false; normalize before scaling (default false).
• body_frame / in_body_frame: apply origin rotation to the vector (default false).
• color: arrow color (default white).
• name: label text; used for legend/overlay (optional).
• show_name: show/hide overlay label (default true).
• arrow_thickness: numeric thickness multiplier with 3-decimal precision (default 0.1).
• label_position: proportionately 0.0–1.0 along the arrow (0=base, 1=tip) for label anchor, or absolutely by specifying a number in a string with an 'm' suffix, .e.g., "0.3m" for 0.3 meters from origin (default "0.1m").

Schema at a glance

Legend: parentheses group alternatives; | means “or”; square brackets [...] are optional; curly braces {...} repeat; * is zero-or-more, + is one-or-more; angle brackets <...> mark positional args.

schematic =
  ( theme
  | window
  | panel
  | object_3d
  | line_3d
  | vector_arrow
  )*

theme = "theme"
      [mode=dark|light]
      [scheme=string]

window = "window"
       [path|file|name=string]
       [title=string]
       [screen=int]
       [rect x y w h]

panel =
  viewport
  | graph
  | component_monitor
  | action_pane
  | query_table
  | query_plot
  | data_overview
  | schematic_tree
  | video_stream
  | dashboard
  | split
  | tabs

split = ("hsplit" | "vsplit")
      [active=bool]
      [name=string]
      { panel [share=float] }+

tabs = "tabs" { panel }+

viewport = "viewport"
         [fov=float]
         [near=float]
         [far=float]
         [aspect=float]
         [active=bool]
         [show_grid=bool]
         [show_arrows=bool]
         [create_frustum=bool]
         [show_frustums=bool]
         [frustums_color=color_name_or_tuple]
         [frustums_thickness=float]
         [hdr=bool]
         [name=string]
         [pos=eql]
         [look_at=eql]
         { vector_arrow }

graph = "graph" eql
      [name=string]
      [type=line|point|bar]
      [lock=bool]
      [auto_y_range=bool]
      [y_min=float]
      [y_max=float]
      { color }*

component_monitor = "component_monitor"
                  [name=string]
                  [component_name=string]

action_pane = "action_pane"
            [name=string]
            [lua=string]

query_table = "query_table"
            [name=string]
            [query=string]
            [type=eql|sql]

query_plot = "query_plot"
           [name=string]
           [query=string]
           [refresh_interval=ms]
           [auto_refresh=bool]
           [color]
           [type=eql|sql]
           [mode=timeseries|xy]
           [x_label=string]
           [y_label=string]

data_overview = "data_overview"
              [name=string]

schematic_tree = "schematic_tree"
               [name=string]

video_stream = "video_stream" <msg_name>
             [name=string]

dashboard      = "dashboard" { dashboard_node }+

object_3d = "object_3d"
          <eql>
          { glb { animate }*
          | sphere
          | box
          | cylinder
          | plane
          | ellipsoid
          }
          [emissivity=float]
          { [visibility_range] }
          [icon]

animate = "animate"
        joint=string
        rotation_vector=eql

icon = "icon"
     (builtin=string | path=string)
     [size=float]
     { [visibility_range] [color] }

visibility_range = "visibility_range"
                 [min=float]
                 [max=float]
                 [fade_distance=float]

line_3d = "line_3d"
        <eql>
        [line_width=float]
        [color]
        [perspective=bool]

vector_arrow = "vector_arrow"
             <vector-eql>
             [origin=eql]
             [scale=float]
             [normalize=bool]
             [body_frame|in_body_frame=bool]
             [color]
             [name=string]
             [show_name=bool]
             [arrow_thickness=float]
             [label_position=0..1]

color = "color"
      ( r g b [a]
      | name [alpha]
      )

OBS Studio Integration

The video_stream panel can display live video from OBS Studio. There are two integration paths:

SRT Receiver (Recommended)

OBS Studio has built-in SRT (Secure Reliable Transport) support. A GStreamer receiver pipeline on the Elodin server demuxes the MPEG-TS stream and forwards H.264 frames to Elodin DB.

OBS configuration: Settings -> Stream -> Custom -> srt://ELODIN_IP:9000?mode=caller

Elodin-side receiver pipeline:

gst-launch-1.0 \
    srtsrc uri="srt://0.0.0.0:9000?mode=listener" ! \
    tsdemux ! \
    h264parse config-interval=-1 ! \
    queue ! \
    elodinsink db-address=127.0.0.1:2240 msg-name="obs-camera"

A convenience script and full example are provided in examples/video-stream/.

obs-gstreamer Direct Pipeline (Alternative)

If the obs-gstreamer plugin is installed on the OBS machine, H.264 can be piped directly into elodinsink without an intermediate process.

OBS output pipeline (configured in obs-gstreamer settings):

video. ! h264parse config-interval=-1 ! elodinsink db-address=ELODIN_IP:2240 msg-name="obs-camera" audio. ! fakesink

This requires both obs-gstreamer and elodinsink to be installed on the OBS machine.

Recommended OBS Encoder Settings

Important: Use H.264, not H.265/HEVC. Elodin's video decoder only supports H.264.

Examples

Minimal viewport + graph:

theme mode="light" scheme="matrix"

viewport name="Main"
         fov=45.0
         active=#true
         show_grid=#true
         pos="drone.world_pos"
         look_at="(0, 0, 0)"
graph "drone.altitude"
      name="Altitude"
      auto_y_range=#true

Video stream panel (e.g. from OBS Studio):

video_stream "obs-camera" name="OBS Camera"

Viewport + video stream side by side:

hsplit {
    viewport name="3D View" show_grid=#true share=0.6
    video_stream "obs-camera" name="OBS Camera" share=0.4
}

Vector arrow with custom color and label:

vector_arrow
  "drone.vel_x,drone.vel_y,drone.vel_z"
  origin="drone.world_pos"
  scale=1.5
  name="Velocity"
  normalize=#true
  body_frame=#true
  arrow_thickness=1.500
  label_position=0.9 {
  color 64 128 255
}

Rigged GLB model with animated joints:

The rotation_vector is an angle-axis: the direction encodes the axis, and the magnitude encodes the angle in degrees.

object_3d rocket.world_pos {
    glb path="rocket.glb"
    animate joint="Root.Fin_0" rotation_vector="(0, rocket.fin_deflect[0], 0)"
    animate joint="Root.Fin_1" rotation_vector="(0, rocket.fin_deflect[1], 0)"
    animate joint="Root.Fin_2" rotation_vector="(0, rocket.fin_deflect[2], 0)"
    animate joint="Root.Fin_3" rotation_vector="(0, rocket.fin_deflect[3], 0)"
}

Distance icon with independent visibility ranges:

object_3d satellite.world_pos {
    glb path="satellite.glb" {
        visibility_range max=500.0
    }
    icon builtin="satellite_alt" {
        visibility_range min=500.0
        color 76 175 80
    }
}

Icon with fade-in (both mesh and icon visible by default, icon fades in over 50 units starting at distance 200):

object_3d drone.world_pos {
    glb path="drone.glb"
    icon path="drone-icon.png" size=48 {
        visibility_range min=200.0 fade_distance=50.0
        color 0 188 212
    }
}

Overlapping ranges (both mesh and icon visible between 400 and 600 units):

object_3d rocket.world_pos {
    glb path="rocket.glb" {
        visibility_range max=600.0
    }
    icon builtin="rocket_launch" {
        visibility_range min=400.0
        color 244 67 54
    }
}

Browse all available built-in icon names at Material Icons (use the snake_case version of the icon name, e.g. "Satellite Alt" becomes satellite_alt).