combine_roads_xld ( EdgePolygons, ModParallels, ExtParallels, CenterLines : RoadSides : MaxAngleParallel, MaxAngleColinear, MaxDistanceParallel, MaxDistanceColinear : )

Combine road hypotheses from two resolution levels.

combine_roads_xld combines road hypotheses obtained from two different resolution levels. The algorithm selects only those hypotheses which mutually support each other in both resolution levels. The parameters EdgePolygons, ModParallels and ExtParallels correspond to the road hypotheses from the highest resolution level. The parameter CenterLines is the result of road extraction in a lower resolution level. Of the polygons EdgePolygons those are returned for which evidence of being roadsides is found in both resolution levels. The parameters MaxAngleParallel and MaxAngleColinear detemine the angle two parallel or collinear line segments are allowed to form, respectively. The parameters MaxDistanceParallel and MaxDistanceColinear determine the maximum allowed distance of two parallel or colliear line segments, respectively. The combination is done using a number of rules.


Parameters

EdgePolygons (input_object)
xld_poly-array -> object
XLD polygons to be examined.

ModParallels (input_object)
xld_mod_para-array -> object
Modified parallels obtained from EdgePolygons.

ExtParallels (input_object)
xld_ext_para-array -> object
Extended parallels obtained from EdgePolygons.

CenterLines (input_object)
xld_poly-array -> object
Road-center-line polygons to be examined.

RoadSides (output_object)
xld_poly-array -> object
Roadsides found.

MaxAngleParallel (input_control)
angle.rad -> real / integer
Maximum angle between two parallel line segments.
Default value: 0.523598775598
Suggested values: 0.349065850399, 0.523598775598, 0.6981317008
Restriction: (0 <= MaxAngleParallel) <= (pi / 2)

MaxAngleColinear (input_control)
angle.rad -> real / integer
Maximum angle between two collinear line segments.
Default value: 0.261799387799
Suggested values: 0.174532925199, 0.261799387799, 0.349065850399
Restriction: (0 <= MaxAngleColinear) <= (pi / 2)

MaxDistanceParallel (input_control)
real -> real / integer
Maximum distance between two parallel line segments.
Default value: 40
Suggested values: 20, 30, 40, 50, 60
Restriction: MaxDistanceParallel > 0

MaxDistanceColinear (input_control)
real -> real / integer
Maximum distance between two collinear line segments.
Default value: 40
Suggested values: 20, 30, 40, 50, 60
Restriction: MaxDistanceColinear > 0


Possible Predecessors

mod_para_xld, poly_xld, scale_cont_xld


Possible Successors

get_poly_xld, get_lines_xld


See also

lines_gauss, lines_facet, edges__, edges_sub_pix


References

C. Steger, C. Glock, W. Eckstein, H. Mayer, B. Radig; "Model-based Road Extraction from Images"; in "Automatic Extraction of Man-Made Objects from Aerial and Space Images"; A. Gruen, O. Kuebler, P. Agouris (Editors); Birkhäuser Verlag (1995), pp. 275-284.

C. Heipke, C. Steger, R. Multhammer; "A Hierarchical Approach to Automatic Road Extraction from Aerial Imagery"; in "Integrating Photogrammetric Techniques with Scene Analysis and Machine Vision II"; D. M. McKeown, Jr., I. J. Dowman (Editors); Proc. SPIE 2486 (1995), pp. 222-231.



Copyright © 1996-1997 MVTec Software GmbH