Image preprocessing

The tool includes image preprocessing algorithms. Two completely different approaches were established. For images with high quality textural information a contrast preserving decolorization algorithm ensuring the conservation of contrast levels between pixels is offered. For those cases with low quality textural information the tool implements the "Wallis" filter able to enhance and improve the texture detail.

Tie points extraction and matching

The tool implements different algorithms for extracting tie points. For those cases where images optical axis convergence is almost null, Tapioca SIFT (Scale-Invariant Feature Transform) implementation is the most effective and efficient solution. For those cases of convergent photogrammetry, a variant of SIFT algorithm robust against affine transformations between images (Affine Scale-Invariant Feature Transform) is implemented. It also has an implementation of novel algorithm MSD (Maximal Self-Dissimilarities) able to not only to deal with RGB images but also is effective with images of different spectral ranges.

Orientation

GRAPHOS implements an aerotriangulation stretegy able to solve not only the relative orientation of each image in space, but also is able to perform an autocalibration of the camera according to different distortion models optimizing the results to ensure a satisfactory densification process.

Dense matching

GRAPHOS includes different dense matching strategies able to solve the different scenarios that we can find. As a result we get a 3D model whose density is able to match the total number of pixels of the images involved in the process.

Gallery

Architectural photogrammetry from UAVs

Reconstruction of architectural elements through images obtained with unmanned aerial vehicles (UAV's).

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High-Precision Macro-Photogrammetry

Reconstruction of reduced size elements with micron accuracy using images obtained using macro lenses.

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Terrestrial close range photogrammetry

3D reconstruction using terrestrial photogrammetry.

Conventional aerial photogrammetry

3D reconstruction of large surfaces using images taken from manned or unmanned aerial platforms.

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