SAM 3 是对 SAM 2 的重大扩展,引入了 Promptable Concept Segmentation (PCS) 任务:给定一个短语名词短语(如 "yellow school bus")、图像范例(image exemplars),或二者的组合,模型自动检测、分割并追踪图像/视频中所有匹配该概念的实例,同时保留跨帧的目标身份。SAM 3 在 PCS 任务上比现有系统提升约 2×,并在交互式视觉分割(PVS)基准上持续优于 SAM 2。SAM 3 is a major extension of SAM 2 that introduces the Promptable Concept Segmentation (PCS) task: given a short noun phrase (e.g. "yellow school bus"), image exemplars, or a combination of both, the model automatically detects, segments and tracks every instance matching that concept in an image or video, while preserving object identity across frames. SAM 3 improves over existing systems by about 2× on PCS, and consistently outperforms SAM 2 on the interactive visual segmentation (PVS) benchmark.
SAM 1 和 SAM 2 开创了交互式分割先河,但它们依赖点、框、掩码等几何提示,每次只能分割单个目标实例,无法回答"视频中所有的猫在哪里"这类概念级查询。现实应用(机器人、内容创作、AR、数据标注、科学研究)迫切需要一个能够理解视觉概念、并一次性找出所有匹配实例的模型。SAM 1 and SAM 2 pioneered interactive segmentation, but they rely on geometric prompts such as points, boxes and masks and can segment only a single object instance at a time, so they cannot answer concept-level queries such as "where are all the cats in this video". Real applications (robotics, content creation, AR, data annotation, scientific research) urgently need a model that understands visual concepts and finds all matching instances at once.
"SAM 1 and SAM 2 focus on visual prompts and segment a single object instance per prompt … they did not address the broader task of finding and segmenting all instances of a concept appearing anywhere in the input."
SAM 3 由共享视觉骨干网络 Perception Encoder (PE) 的 检测器(图像级)与 追踪器(内存式视频)构成。检测器基于 DETR 范式,输入文本/图像范例提示后预测所有匹配实例的分割掩码。追踪器继承 SAM 2 的 Transformer 编解码器架构,在视频中传播 masklet(时空掩码)。两者通过四阶段渐进式训练策略联合优化。SAM 3 consists of a detector (image level) and a tracker (memory-based video) that share a Perception Encoder (PE) visual backbone. The detector follows the DETR paradigm and, given text or image-exemplar prompts, predicts segmentation masks for all matching instances. The tracker inherits the Transformer encoder-decoder architecture of SAM 2 and propagates masklets (spatio-temporal masks) through the video. The two are optimised jointly with a four-stage progressive training strategy.
传统 DETR 中每个 proposal query 既要识别(what)又要定位(where),两者目标冲突:识别需要全局上下文,而定位本质上是局部的。SAM 3 引入一个可学习的全局 presence token,专门预测目标概念是否出现在图像/帧中(p(NP is present in input))。每个 proposal query 只需在"概念已出现"的条件下解决定位问题,最终分数 = 自身分数 × presence 分数。消融实验显示该设计将 SA-Co/Gold CGF1 提升 +5.7(从 57.6 到 63.3),image-level MCC 从 0.77 提升至 0.82。In a conventional DETR, every proposal query has to both recognise (what) and localise (where), and the two objectives conflict: recognition needs global context, whereas localisation is intrinsically local. SAM 3 introduces a learnable global presence token dedicated to predicting whether the target concept appears in the image/frame (p(NP is present in input)). Each proposal query then only has to solve localisation conditioned on the concept being present, and the final score = its own score × the presence score. Ablations show that this design raises SA-Co/Gold CGF1 by +5.7 (from 57.6 to 63.3) and image-level MCC from 0.77 to 0.82.
SAM 3 支持图像范例提示(正框 / 负框),可单独使用或与文本提示组合。每个范例由位置嵌入、标签嵌入及 ROI 池化视觉特征拼接后经小型 Transformer 编码,与文本 token 拼接共同构成 prompt tokens。交互式地加入范例后,模型能泛化地检测/抑制相似目标(而不仅修正单个实例),3 次点击后比文字提示提升 +18.6 CGF1,比理想 PVS 修正提升 +9.7。SAM 3 supports image-exemplar prompts (positive / negative boxes), used on their own or combined with a text prompt. Each exemplar is encoded by a small Transformer over the concatenation of its position embedding, label embedding and ROI-pooled visual features, and is concatenated with the text tokens to form the prompt tokens. Once exemplars are added interactively, the model detects/suppresses similar objects in a generalising way (rather than merely correcting a single instance): after three clicks it improves over the text prompt by +18.6 CGF1, and over ideal PVS correction by +9.7.
给定视频与提示 P,检测器在每帧上发现新目标 Ot,追踪器将前一时刻的 masklet Mt-1 传播到当前帧得到 M̂t,随后通过基于 IoU 的匹配函数将二者关联并更新。对于遮挡/干扰物等追踪失败场景,SAM 3 引入两项时序消歧策略:masklet detection score(时序窗口内持续匹配得分)和定期用高置信度检测结果重新初始化追踪器内存库。Given a video and a prompt P, the detector discovers new objects Ot in every frame, while the tracker propagates the masklet Mt-1 of the previous time step into the current frame to obtain M̂t; the two are then associated and updated through an IoU-based matching function. For tracking failures caused by occlusion or distractors, SAM 3 introduces two temporal disambiguation strategies: a masklet detection score (a sustained matching score within a temporal window) and periodic re-initialisation of the tracker memory bank with high-confidence detections.
数据引擎分四阶段迭代:The data engine iterates over four phases:
SAM 3 在图像/视频 PCS(开放词汇实例分割与追踪)、少样本适应(目标检测/计数)以及与 MLLM 结合的复杂语言查询分割等任务上进行全面评估。评测基准涵盖 LVIS、COCO、SA-Co/Gold/Silver/Bronze/Bio、SA-Co/VEval、ODinW13、RF-100VL、ReasonSeg、OmniLabel 等。SAM 3 is evaluated comprehensively on image/video PCS (open-vocabulary instance segmentation and tracking), few-shot adaptation (object detection/counting) and segmentation from complex language queries in combination with an MLLM. The benchmarks cover LVIS, COCO, SA-Co/Gold/Silver/Bronze/Bio, SA-Co/VEval, ODinW13, RF-100VL, ReasonSeg, OmniLabel and others.
| 基准Benchmark | 指标Metric | 前最优基线Previous best baseline | SAM 3 | 提升Gain |
|---|---|---|---|---|
| LVIS(实例分割)LVIS (instance segmentation) | mask AP | 38.5 (DINO-X) | 47.0 | +8.5 |
| SA-Co/Gold(PCS)SA-Co/Gold (PCS) | CGF1 | 36.3 (OWLv2*) | 65.0 | 约 2×about 2× |
| SA-Co/Gold(框检测)SA-Co/Gold (box detection) | CGF1 | 53.0 (LLMDet-L) | 59.3 | +6.3 |
| ADE-847(语义分割)ADE-847 (semantic segmentation) | mIoU | 29.4 (APE-D*) | 53.1 | +23.7 |
| Cityscapes(语义分割)Cityscapes (semantic segmentation) | mIoU | 44.2 (APE-D*) | 59.4 | +15.2 |
注:SA-Co/Gold CGF1 = 65.0 达到人类下限估计(74.2)的 88%。Gemini 2.5(强通用 LLM 基线)CGF1 为 19.8,SAM 3 超出其约 3.3×。Note: SA-Co/Gold CGF1 = 65.0 reaches 88% of the estimated human lower bound (74.2). Gemini 2.5, a strong general-purpose LLM baseline, reaches a CGF1 of 19.8, which SAM 3 exceeds by about 3.3×.
| 数据集Dataset | 提示类型Prompt type | T-Rex2(前最优)T-Rex2 (previous best) | SAM 3 |
|---|---|---|---|
| COCO | T+I | — | 62.5 |
| LVIS | T+I | — | 77.0 |
| ODinW35 | T+I | — | 79.6 |
| COCO(文本 T)COCO (text T) | T | 52.2 | 53.5 (+1.3) |
| ODinW35(文本 T)ODinW35 (text T) | T | 50.3 | 59.9 (+9.6) |
| 数据集Dataset | 指标Metric | 前最优基线Previous best baseline | SAM 3 |
|---|---|---|---|
| SA-Co/VEval SA-V | pHOTA | 49.0 (LLMDet + SAM 3 Tracker) | 53.9 |
| SA-Co/VEval YT-Temporal-1B | pHOTA | 44.6 | 69.2 |
| SA-Co/VEval SmartGlasses | pHOTA | 57.1 (SAM 3 Det + T-by-D) | 62.9 |
| LVVIS(test mAP) | mAP | 57.3 | 56.9 |
| MOSEv2(VOS J&F) | J&F | 53.8 (SeC) | 60.1 (+6.3) |
SA-Co/VEval 上 SAM 3 达到人类 pHOTA 下限的 >80%。GLEE 基线(未在 SA-Co 上训练)CGF1 接近 0,突出了大规模多概念视频分割的难度。On SA-Co/VEval, SAM 3 reaches >80% of the human pHOTA lower bound. The CGF1 of the GLEE baseline (not trained on SA-Co) is close to 0, which highlights how difficult large-scale multi-concept video segmentation is.
模拟人机协作:从文本提示出发,每轮迭代添加一个正/负范例框。实验显示:Simulating human-model collaboration: starting from a text prompt, one positive/negative exemplar box is added per iteration. The experiments show that:
| 模型Model | CountBench Acc↑ | PixMo-Count Acc↑ |
|---|---|---|
| DINO-X | 82.9 | 85.0 |
| Gemini 2.5 Pro | 92.4 | 78.2 |
| Molmo-72B | 92.4 | 88.8 |
| SAM 3 | 95.6 | 87.3 |
SAM 3 可与多种 MLLM(Qwen2.5-VL 7B/72B、Llama4 Maverick、Gemini 2.5 Pro)结合,MLLM 将复杂语言查询分解为 NP 调用 SAM 3,迭代优化输出。零样本情况下在 ReasonSeg 和 OmniLabel 上分别达到 73.8 gIoU 和 46.7 AP,超越所有专用方法(包括 GPT-4o + SegZero 等)。SAM 3 can be combined with a variety of MLLMs (Qwen2.5-VL 7B/72B, Llama4 Maverick, Gemini 2.5 Pro): the MLLM decomposes a complex language query into NPs, calls SAM 3 and iteratively refines the output. Zero-shot, it reaches 73.8 gIoU on ReasonSeg and 46.7 AP on OmniLabel, surpassing all specialised methods (including GPT-4o + SegZero).
| 消融项Ablation | 设置Setting | CGF1 | IL MCC | pmF1 |
|---|---|---|---|---|
| Presence Token | 无without | 57.6 | 0.77 | 74.7 |
| 有with | 63.3 | 0.82 | 77.1 | |
| 训练数据Training data | 仅 EXTEXT only | 30.9 | 0.46 | 66.3 |
| EXT + SYN | 39.7 | 0.57 | 70.6 | |
| EXT + SYN + HQ | 54.3 | 0.74 | 73.5 | |
| 硬负例(每图 #)Hard negatives (# per image) | 0 个0 | 31.8 | 0.44 | 70.2 |
| 5 个5 | 44.8 | 0.62 | 71.9 | |
| 30 个30 | 49.2 | 0.68 | 72.3 |
消融验证:Presence Token(+5.7 CGF1)、硬负例训练(IL MCC 从 0.44 大幅提升至 0.68)、高质量人工数据 HQ(比纯合成数据 SYN 再提升 +14.6 CGF1)均是关键贡献。The ablations confirm the key contributions: the Presence Token (+5.7 CGF1), hard-negative training (IL MCC rising sharply from 0.44 to 0.68) and high-quality human data HQ (a further +14.6 CGF1 over purely synthetic SYN data).
"SAM 3 struggles to generalize to fine-grained out-of-domain concepts (e.g., aircraft types, medical terms) in a zero-shot manner, especially in niche visual domains (e.g., thermal imagery)." 虽然少量微调可快速适应新概念,但零样本表现有限。"SAM 3 struggles to generalize to fine-grained out-of-domain concepts (e.g., aircraft types, medical terms) in a zero-shot manner, especially in niche visual domains (e.g., thermal imagery)." A small amount of fine-tuning can adapt the model to new concepts quickly, but zero-shot performance remains limited.
"SAM 3 is constrained to simple noun phrase prompts and does not support multi-attribute queries beyond one or two attributes or longer phrases including referring expressions." 即不直接支持复杂指代表达。与 MLLM 结合可缓解此问题,但需要外部大模型参与。"SAM 3 is constrained to simple noun phrase prompts and does not support multi-attribute queries beyond one or two attributes or longer phrases including referring expressions." In other words, complex referring expressions are not supported directly. Combining SAM 3 with an MLLM alleviates the problem, but requires an external large model.
"The cost of SAM 3 inference scales linearly with the number of objects being tracked." 实时 30 FPS 需要多卡并行:2×H200 支持约 10 个目标,4×H200 支持约 28 个,8×H200 支持约 64 个。"There is no shared object-level contextual information to aid in resolving ambiguities in multi-object tracking scenarios.""The cost of SAM 3 inference scales linearly with the number of objects being tracked." Real-time 30 FPS requires multi-GPU parallelism: 2×H200 supports about 10 objects, 4×H200 about 28, and 8×H200 about 64. "There is no shared object-level contextual information to aid in resolving ambiguities in multi-object tracking scenarios."
"Supporting concept-level interactivity for PCS, alongside instance-level interactivity for PVS, poses several challenges. To support instance-level modifications without affecting all other instances of the concept, we enforce a hard 'mode-switch' within the model from concept to instance mode." 作者指出,未来工作可以更无缝地交织概念提示与实例提示。"Supporting concept-level interactivity for PCS, alongside instance-level interactivity for PVS, poses several challenges. To support instance-level modifications without affecting all other instances of the concept, we enforce a hard 'mode-switch' within the model from concept to instance mode." The authors point out that future work could interleave concept prompts and instance prompts more seamlessly.