Download the OpenSim Model for an OpenCap Session

Downloads the subject-specific, scaled OpenSim model (.osim) that OpenCap produced for a session. This model is the input the local OpenSim toolchain needs (runOpenSimFromMarkers / runOpenSimFromOpenCap): OpenCap builds and scales it in the cloud from the neutral/calibration trial, and PhysioOpenSim provides no scaling tool of its own, so the model must come from OpenCap.

Usage

downloadOpenCapModel(
  session_id,
  trial_id = NULL,
  api_key = NULL,
  base_url = "https://app.opencap.ai/api",
  dest = NULL
)

Arguments

session_id: Character string giving the OpenCap session identifier (the 36-character UUID at the end of the session URL).
trial_id: Character string giving the trial identifier within the session. If NULL (default), the first trial in the session is used.
api_key: Character string with the OpenCap API key. If NULL (default), the key is read from the OPENCAP_API_KEY environment variable.
base_url: Character string giving the base URL for the OpenCap API. Default is "https://app.opencap.ai/api".
dest: Character path to write the model to. If NULL (default) a temporary .osim file is created.

Value

The local path to the downloaded .osim model (invisibly).

Details

Requires the httr package and an OpenCap API key (see readOpenCap). The model URL is taken from the session metadata when present and otherwise constructed from the documented session endpoint.

References

Uhlrich SD, Falisse A, Kidzinski L, Muccini J, Ko M, Chaudhari AS, Hicks JL, Delp SL (2023). "OpenCap: Human movement dynamics from smartphone videos." PLoS Computational Biology, 19(10), e1011462.

Examples

if (FALSE) { # \dontrun{
osim <- downloadOpenCapModel("abcd1234-5678-90ab-cdef-1234567890ab")
} # }