sam2/build_sam.py

# Copyright (c) Meta Platforms, Inc. and affiliates.
# All rights reserved.

# This source code is licensed under the license found in the
# LICENSE file in the root directory of this source tree.

import logging

import torch
from hydra import compose
from hydra.utils import instantiate
from omegaconf import OmegaConf

from .utils.misc import VARIANTS, variant_to_config_mapping


def load_model(
    variant: str,
    ckpt_path=None,
    device="cpu",
    mode="eval",
    hydra_overrides_extra=[],
    apply_postprocessing=True,
) -> torch.nn.Module:
    assert variant in VARIANTS, f"only accepted variants are {VARIANTS}"

    return build_sam2(
        config_file=variant_to_config_mapping[variant],
        ckpt_path=ckpt_path,
        device=device,
        mode=mode,
        hydra_overrides_extra=hydra_overrides_extra,
        apply_postprocessing=apply_postprocessing,
    )


def build_sam2(
    config_file,
    ckpt_path=None,
    device="cpu",
    mode="eval",
    hydra_overrides_extra=[],
    apply_postprocessing=True,
):

    if apply_postprocessing:
        hydra_overrides_extra = hydra_overrides_extra.copy()
        hydra_overrides_extra += [
            # dynamically fall back to multi-mask if the single mask is not stable
            "++model.sam_mask_decoder_extra_args.dynamic_multimask_via_stability=true",
            "++model.sam_mask_decoder_extra_args.dynamic_multimask_stability_delta=0.05",
            "++model.sam_mask_decoder_extra_args.dynamic_multimask_stability_thresh=0.98",
        ]
    # Read config and init model
    cfg = compose(config_name=config_file, overrides=hydra_overrides_extra)
    OmegaConf.resolve(cfg)
    model = instantiate(cfg.model, _recursive_=True)
    _load_checkpoint(model, ckpt_path)
    model = model.to(device)
    if mode == "eval":
        model.eval()
    return model


def build_sam2_video_predictor(
    config_file,
    ckpt_path=None,
    device="cpu",
    mode="eval",
    hydra_overrides_extra=[],
    apply_postprocessing=True,
):
    hydra_overrides = [
        "++model._target_=sam2.sam2_video_predictor.SAM2VideoPredictor",
    ]
    if apply_postprocessing:
        hydra_overrides_extra = hydra_overrides_extra.copy()
        hydra_overrides_extra += [
            # dynamically fall back to multi-mask if the single mask is not stable
            "++model.sam_mask_decoder_extra_args.dynamic_multimask_via_stability=true",
            "++model.sam_mask_decoder_extra_args.dynamic_multimask_stability_delta=0.05",
            "++model.sam_mask_decoder_extra_args.dynamic_multimask_stability_thresh=0.98",
            # the sigmoid mask logits on interacted frames with clicks in the memory encoder so that the encoded masks are exactly as what users see from clicking
            "++model.binarize_mask_from_pts_for_mem_enc=true",
            # fill small holes in the low-res masks up to `fill_hole_area` (before resizing them to the original video resolution)
            # "++model.fill_hole_area=8",
        ]
    hydra_overrides.extend(hydra_overrides_extra)

    # Read config and init model
    cfg = compose(config_name=config_file, overrides=hydra_overrides)
    OmegaConf.resolve(cfg)
    model = instantiate(cfg.model, _recursive_=True)
    _load_checkpoint(model, ckpt_path)
    model = model.to(device)
    if mode == "eval":
        model.eval()
    return model


def _load_checkpoint(model, ckpt_path):
    if ckpt_path is not None:
        sd = torch.load(ckpt_path, map_location="cpu", weights_only=True)["model"]
        missing_keys, unexpected_keys = model.load_state_dict(sd)
        if missing_keys:
            logging.error(missing_keys)
            raise RuntimeError()
        if unexpected_keys:
            logging.error(unexpected_keys)
            raise RuntimeError()
        logging.info("Loaded checkpoint sucessfully")