1. A pose estimation system provided with a first data processing device, a second processing device and a data process switching device, said first data processing device comprising: a binarization unit for dividing an image received as input into a candidate region that is a candidate for a reference surface that serves as a reference for estimating pose and a background region that is a region other than the candidate region; a surface parameter formula expression unit for extracting pose parameters that indicate pose of an object of pose estimation with respect to a reference surface that appears in said image that was received as input and, based on a combination of values obtained by implementing a transform by a prescribed function upon, of the pose parameters that were extracted, parameters that indicate the direction in which the object of pose estimation is directed and pose parameters other than the parameters that indicate direction, finding surface parameter formulas that are numerical formulas that express said reference surface; a parameter computation unit for, based on pose parameters that were extracted by said surface parameter formula expression unit, computing the combination of pose parameters that make up said surface parameter formulas that express all surfaces that pass through each pixel contained in the candidate region that was divided by said binarization unit; a parameter surface drawing unit for, based on the combination of pose parameters computed by said parameter computation unit, drawing parameter surfaces in accordance with said surface parameter formulas on parameter space, which is space that includes each of the parameters belonging to said pose parameters as the axes of base vectors; an intersection detection unit for finding cross point coordinates, which are the coordinates of intersections through which pass a plurality of said parameter surfaces that were drawn by said parameter surface drawing unit, and a cross surface number, which is the number of parameter surfaces that pass through the cross point coordinates; a significant candidate extraction unit for, when the cross surface number at each cross point that was found by said intersection detection unit is compared with cross surface numbers at other cross point coordinates in prescribed neighboring regions that take as a reference the cross point coordinate corresponding to the cross surface number and is thus determined to be a maximum, identifying the combination of pose parameters that make up the parameter surface that corresponds to the determined cross surface number as a significant candidate that is an optimum combination of pose parameters for expressing said reference surface; a significant candidate surface drawing unit for, based on a significant candidate identified by said significant candidate extraction unit and a combination of pose parameters that were computed by said parameter computation unit for which distance to said significant candidate in parameter space in prescribed neighboring regions that take the significant candidate as a reference is no greater than a prescribed value, drawing significant candidate surfaces on said image; a cross determination unit for, regarding each significant candidate surface that was drawn by said significant candidate surface drawing unit, identifying pixels that are located on, of said candidate region, the significant candidate surface, and pixels that are located within a prescribed range from the significant candidate surface as cross pixels and finding coordinates of the cross pixels and tangent planes at said cross pixels; a weighting computation unit for, based on angles that are formed by tangent planes in cross pixels that were found by said cross determination unit and planes that are formed by the axes of each base vector included in said parameter space, finding a slope weighting for each cross pixel that was identified by said cross determination unit; a number measurement unit for computing for each of said significant candidate surfaces a number that is the value obtained by adding up the slope weightings of cross pixels that were found by said weighting computation unit and that were contained in each of the significant candidates; and an actual surface determination unit for, when the number computed by said number measurement unit is compared with a number belonging to other significant candidate surfaces in neighboring regions that take as a reference the significant candidate surface that has this number and that thus is determined to be a maximum, identifying the significant candidate surface having said determined number as an actual surface that is a reference surface that actually exists in said image: said second data processing device for, based on an image received as input, estimating pose of an object of pose estimation with respect to a reference surface that serves as a reference for estimating pose, said second data processing device comprising: a binarization unit for dividing said image into a candidate region that is a candidate for said reference surface and a background region that is a region other than the candidate region; a surface parameter formula expression unit for extracting pose parameters that indicate the pose of an object of pose estimation with respect to a reference surface that appears in said image that was received as input and, based on the combination of a value obtained by implementing a transform by a prescribed function upon, of the pose parameters that were extracted, parameters that indicate a direction in which the object of the pose estimation is directed and pose parameters other than the parameters that indicate direction, finding surface parameter formulas that are numerical formulas that express said reference surface; an all-candidate surface drawing unit for, based on the combination of all pose parameters in parameter space, which is space having, as the axes of base vectors, each of the parameters included in said pose parameters, drawing candidate surfaces that accord with said surface parameter formulas on said image in said parameter space; a cross determination unit for, as regards each candidate surface that was drawn by said all-candidate surface drawing unit, identifying pixels that are located on, of said candidate region, the candidate surface, and pixels that are located within a prescribed range from the candidate surface as cross pixels and finding coordinates of the cross pixels and tangent planes at said cross pixels; a weighting computation unit for, based on angles that are formed by tangent planes at the cross pixels that were found by said cross determination unit and planes that are formed by the axes of each base vector included in said parameter space, finding a slope weighting for each cross pixel that was identified by said cross determination unit; a number measurement unit for computing for each of said candidate surfaces a number that is the value obtained by adding up the slope weightings of cross pixels that were found by said weighting computation unit and that were contained in each of the candidate surfaces; and an actual surface determination unit for, based on the number computed by said number measurement unit, identifying from among candidate surfaces drawn by said all-candidate surface drawing unit an actual surface that is a reference surface that actually exists in said image: said data process switching device for, based on the results of comparing a parameter space calculation amount, which is a calculation amount indicating the volume of arithmetic processing by the first data processing device to realize identification of an actual surface that is said reference surface, and an image space calculation amount, which is a calculation amount indicating the volume of arithmetic processing by the second data processing device to realize identification of an actual surface, selecting the first data processing device or the second data processing device and causing the selected data processing device to identify said actual surface.