Object Detection
A RocketRide image node that detects objects in each input frame and emits labeled bounding boxes plus an annotated image. Choose it when downstream work needs object locations; use Segmentation when it needs pixel masks instead.
About RF-DETR and MM-Grounding-DINO
RF-DETR and MM-Grounding-DINO are the two detection backends exposed by this node. RF-DETR is the default common-object profile, while MM-Grounding-DINO is the prompt-driven open-vocabulary profile; the node supplies the selected backend, threshold, prompt, and optional revision to its detector.
What it does
The node buffers each completed image stream, runs the selected detector, and can emit the detections as JSON and a JPEG annotated with boxes and labels. RF-DETR detects the configured profile's common-object class set; MM-Grounding-DINO lets the prompt define the desired objects or attributes. Choose it as a per-frame gate or whenever location, confidence, and centroid data matter, rather than choosing Caption for a prose description or Segmentation for masks.
Lanes
| Lane in | Lane out | Description |
|---|---|---|
image | image | JPEG copy of the source image annotated with detection boxes and labels. |
image | text | JSON array of detections with label, score, box, and centroid. |
Profiles
Default: RF-DETR — Common Objects (COCO, 80 classes, default) (rfdetr).
| Profile | Backend | Use |
|---|---|---|
| RF-DETR — Common Objects (COCO, 80 classes, default) (default) | rfdetr | Closed-set common-object detection. |
| MM-Grounding-DINO — Open-Vocabulary (any prompt) | mmgdino | Prompt-driven open-vocabulary detection. |
Configuration
Start with the RF-DETR profile for the provided common-object detector. Switch to MM-Grounding-DINO when the sought object must be expressed in a prompt, then set a threshold to control which matched regions reach downstream nodes.
Model
The RF-DETR profile is the default and supplies the rfdetr engine. The MM-Grounding-DINO profile supplies the mmgdino engine and makes the detection prompt visible in the configuration panel. If the runtime receives an unrecognized engine value, it logs a warning and uses its default backend instead; use one of the supplied profiles to avoid silently falling back.
Detection prompt
This field is required for the prompt-driven MM-Grounding-DINO backend: startup fails when that backend has no non-empty prompt. It accepts period- or comma-separated terms, such as person . car . dog; the runtime splits either separator into the classes it passes to the detector. Use it to name objects or describe attributes such as red car or person in a hat. The field description explicitly warns that spatial relationships are not supported, so a prompt such as the car on the left can return all cars rather than only the left one.
Confidence threshold
The threshold is a 0.0–1.0 minimum confidence for including a detection, with 0.3 as the default in both supplied profiles. Raise it when low-confidence boxes are creating noisy downstream work; lower it when missed candidates matter more than precision. If the runtime receives a non-numeric or out-of-range value, it logs a warning and uses its detector default threshold.
Requirements
With a model server configured, detection runs there. Otherwise it runs locally on CPU, Apple Silicon (MPS), or CUDA, and a device lock serializes local inference.
Notes
Output and failures
The image output draws lime rectangles and labels containing each detection's label and score. If image decoding, detection, or output generation fails for a frame, the node logs a warning, drops that frame, and emits no image or text output for it.
Upstream docs
Schema
| Field | Type | Description | Default |
|---|---|---|---|
detect.profile | string | Model | "rfdetr" |
detect.prompt | string | Detection prompt Example: "person . car . dog" (period or comma-separated list) or "red car" / "person in a hat" (described object). Returns all matching regions. Matches objects and attributes — not spatial relationships, so "the car on the left" returns all cars, not just the left one. | |
detect.threshold | number | Confidence threshold Minimum confidence score (0.0–1.0) to include a detection | 0.3 |