Vertices Of Parallelogram Research Articles

Accurate Self-calibration of Camera with Variable Intrinsic Parameters from Unknown 3D Scene

In this article we present a practical self-calibration method of camera having variable intrinsic parameters. This method is an extension of a method which we have already published. The main idea of our method addressed in this paper is the use of interest points automatically detected in two images of an unknown 3D scene to self-calibrate the camera. These interest points are the projections of the vertices of unknown 3D parallelograms (each triplet of interest points is the projections of three vertices of a unique 3D parallelogram). The projection of the vertices of parallelograms in the two image planes of the camera allows us to obtain two equations based on the intrinsic camera parameters. Seeing that our camera can change its intrinsic parameters from a view to another so the number of unknowns is ten hence the need to use at least five parallelograms in the scene to obtain other equations in function of intrinsic camera parameters. The paper tests the performance of the proposed approach on the both synthetic and real data.

Structural variation in silver(I) complexes with pyridazine ligand and aromatic polycarboxylic acids: Structural analysis with silver chains

To systematically explore the influence of pyridazine ligands and aromatic polycarboxylate on the existence of argentophilicity, four inorganic–organic hybrid Ag(I) complexes were obtained by one-pot ultrasonic reaction. Four complexes were named [Ag6(pdz)2(btc)2]n (1), [Ag2(pdz)(npt)]n (2), [Ag2(pdz)(pma)1/2]n (3), and [Ag2(pdz)(npa)·H2O]n (4) (pdz=pyridazine, H3btc=1,3,5-benzene tricarboxylic, H2npt=3-nitrophthalic acid, H4pma=pyromellitic acid, H2npa=1,4-naphthalenedicarboxylic acid). Structural analyses reveal that complexes 1–4 display diverse 2D or 3D frameworks, which all of the N-donor pdz ligands exhibit the same coordination mode but the distances of the silver atoms which link to the pdz ligands are different to each other. Complex 1 shows Ag6 clusters and the cluster is comprised by two distorted tetrahedron silver units. And the clusters are shared by two silver ions to form 1D silver chains. Complex 2 features 1D silver chains which are formed by the Ag4 units and the four Ag(I) ions are in the vertices of parallelogram. Complex 3 is an interpenetrating architecture with the pdz ligands alternately repeating up and down in ac plane. The structure of complex 4 is a 2D layer structure which the pdz and npt ligands alternately repeat along a axis. Moreover, complexes 1–4 indicate different photoluminescence behaviors in the solid state.