How to download a 2:1 equirectangular panorama as JPEG using only pano and build IDs?

[tassilo-net]

Hi,

I'm trying to download a 2:1 equirectangular panorama (JPEG format) using the streetlevel library, but I want to do this only by providing the panorama ID (pano_id) and build ID (build_id), without specifying latitude and longitude.

Most examples and methods I found require latitude and longitude to create a LookaroundPanorama object or fetch metadata, but I would prefer to avoid that if possible and rely solely on the IDs.

Could you please advise if this is possible with the current API? If yes, could you provide an example or guidance on how to do this?

Thanks a lot for your help!

Best regards

[sk-zk]

This is possible, but in order to reproject the panorama correctly, its projection parameters must be known. These parameters cannot be inferred from the IDs alone, but, luckily, there are only three different sets of parameters currently in use, and they can be inferred from the image sizes. This may change in the future though.

Anyway, here's the script:

import io
import math

from streetlevel import lookaround
from streetlevel.lookaround.panorama import LookaroundPanorama, CameraMetadata, \
    LensProjection, OrientedPosition

from PIL import Image
from pillow_heif import register_heif_opener


def build_camera_metadata_object(fov_h_sides, cy_sides, fov_s_5, fov_h_5):
    return [
        CameraMetadata(
            LensProjection(2.159844949, fov_h_sides, 0, 0, 0, 0, cy_sides, 0, 0),
            OrientedPosition(0, 0, 0, 0, 0, 0)),
        CameraMetadata(
            LensProjection(1.178097245, fov_h_sides, 0, 0, 0, 0, cy_sides, 0, 0),
            OrientedPosition(0, 0, 0, math.pi / 2, 0, 0)),
        CameraMetadata(
            LensProjection(2.159844949, fov_h_sides, 0, 0, 0, 0, cy_sides, 0, 0),
            OrientedPosition(0, 0, 0, math.pi, 0, 0)),
        CameraMetadata(
            LensProjection(1.178097245, fov_h_sides, 0, 0, 0, 0, cy_sides, 0, 0),
            OrientedPosition(0, 0, 0, -math.pi / 2, 0, 0)),
        CameraMetadata(
            LensProjection(1.047197551, 1.047197551, 0, 0, 0, 0, 0, 0, 0),
            OrientedPosition(0, 0, 0, -0.00038652291956702483, math.pi / 2, math.pi)),
        CameraMetadata(
            LensProjection(fov_s_5, fov_h_5, 0, 0, 0, 0, 0, 0, 0),
            OrientedPosition(0, 0, 0, math.pi, -math.pi / 2, 0))
    ]


def infer_projection_from_face_sizes(faces):
    ratio = faces[0].height / faces[0].width
    if 0.8 < ratio < 0.9:  # "Smallcam" and backpack coverage
        return build_camera_metadata_object(1.8325957, 0.30543262, 2.1293018, 2.268928)
    elif ratio > 0.7:  # "Bigcam" coverage
        return build_camera_metadata_object(1.6144296, 0.27488935, 2.1293018, 2.268928)
    elif ratio > 0.6:  # Switzerland/Liechtenstein 2021-2022 coverage
        return build_camera_metadata_object(1.4398966, 0.36215582, 2.5307274, 2.6179938)
    else:
        raise ValueError("The crude projection detection failed; something must have changed.")


if __name__ == "__main__":
    register_heif_opener()

    zoom = 2  # 0 is biggest, 6 is smallest
    pano_id = 11305468371999655168
    build_id = 2147485020
    auth = lookaround.Authenticator()

    faces = []
    for face_idx in range(0, 6):
        face_heic = lookaround.get_panorama_face((pano_id, build_id), face_idx, zoom, auth)
        face = Image.open(io.BytesIO(face_heic))
        faces.append(face)

    result = lookaround.to_equirectangular(faces, infer_projection_from_face_sizes(faces))
    result.save(f"{pano_id}.jpg", options={"quality": 100})