SfM_georef - georeferencing SfM point clouds

SfM_georef in use

Sfm_georef is software for scaling and geo-referencing structure-from-motion (SfM) point clouds to real-world coordinates, using observations made directly in the SfM image set (rather than identifying and matching features from the point cloud). A valid SfM project is required, and the following reconstruction software and pipelines are currently supported:

For scaling a project, at least one distance (a control length) between positions that can be directly observed in two or more images is needed. For scaling and geo-referencing a project, the real 3D positions of three or more points (control points) that can each be observed in two or more images, is necessary. v2.3 alternatively allows you to provide the camera locations. Once the transform is determined, this can be applied to point cloud (.ply) files generated by Bundler (sparse) or PMVS2 (dense), with provision given for merging multiple files (such as produced by CMVS clustering for PMVS2) into one. Sfm_georef is originally written in Matlab, with recent versions (2.0 and above) compiled into a stand alone application (Windows only).

A table of SfM software and websites is available here Download pdf.

Downloads

If you use sfm_georef, please cite the James and Robson (2012) paper listed below.

    sfm_georef v3.0 - COMING SOON
    • Compatible with PhotoScan
    • Automated target localisation (image matching) – particularly for UAV imagery
    • Sparse points statistics
      sfm_georef v2.3: sfm_georef v2.2: sfm_georef v2.0: sfm_georef v1.0: Fix for Bundler Photogrammetry Package when using images with (capitalised) .JPG extensions.

      Examples

      Geological hand sample

      Montserrat volcanic bomb This volcanic bomb (~10 cm across) from Soufrière Hills volcano was scanned by an Arius3d laser scanner (Stuart Robson, University College London) and also reconstructed using the SfM-MVS technique, with the results scaled by sfm_georef. Differences between cross sections through the two models have RMS values of ~0.3 mm.

      Point cloud: low res (6 Mb)

      Volcanic edifice

      Piton de la Founaise Prior to the more recent collapse of the crater floor, photos were taken of the summit craters of Piton de la Fournaise volcano, Reunion (Ben van Wyk de Vries, Univ. Blaise Pascal, Clermont Ferrand). The resulting SfM-MVS model (top) that was then scaled and geo-referenced using sfm_georef and control targets that were deployed at the time. The positions of the control targets are shown as red triangles on the resulting DEM given below. Coordinate units are metres, and overall RMS of the DEM to one produced from traditional oblique photogrammetry techniques is ~1 m over a viewing distance of ~1 km.

      Reference

      James, M. R. and Robson, S. (2012) Straightforward reconstruction of 3D surfaces and topography with a camera: Accuracy and geoscience application, J. Geophysical Res., 117, F03017, doi:10.1029/2011JF002289

      Associated data:

      Instructions for using Bundler Photogrammetry Package (.pdf).

      Publications using SfM_Georef

      Tuffen, H., James, M. R., Castro, J. M. and Schipper, C. I. (2013) Exceptional mobility of an advancing rhyolitic obsidian flow at Cordón Caulle volcano in Chile, Nature Comms., 4, 2709, doi:10.1038/ncomms3709

      James, M. R. and Quinton, J. (2013) Ultra-rapid topographic surveying for complex environments: The hand-held mobile laser scanner (HMLS), Earth Surf. Proc. Landforms, doi:10.1002/esp.3489 Download pdf

      James, M. R. and Varley, N. (2012) Identification of structural controls in an active lava dome with high resolution DEMs: Volcán de Colima, Mexico, Geophys. Res. Letts., 39, L22303, doi: 10.1029/2012GL054245

      Castillo, C., Pérez, R., James, M. R., Quinton, J. N., Taguas, E. V. and Gómez, J. A. (2012) Comparing the accuracy of several field methods for measuring gully erosion, Soil Sci. Soc. Am. J., 76, 1319-1332, doi: 10.2136/sssaj2011.0390

      James, M. R. and Robson, S. (2012) Straightforward reconstruction of 3D surfaces and topography with a camera: Accuracy and geoscience application, J. Geophysical Res., 117, F03017, doi:10.1029/2011JF002289

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