NURBS-Python
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Published
20 hours ago •
orbingol
orbingol
Help wanted: unknown ZeroDivisionError
this is my code
from geomdl import BSpline
# Create a BSpline surface instance (Bezier surface)
surf = BSpline.Surface()
surf.degree_u=2
surf.degree_v=2
surf.ctrlpts_size_u=5
surf.ctrlpts_size_v=9
surf.ctrlpts=[
(52.5, 60, 0),
(52.5, 60, 60),
(52.5, 0, 60),
(52.5, -59.999999999999986, 60.000000000000007),
(52.5, -60, 0),
(52.5, -60.000000000000007, -59.999999999999986),
(52.5, 0, -60),
(52.5, 60, -60.000000000000021),
(52.5, 60, 0),
(17.500000000000004, 59.999999999999986, 0),
(17.5, 59.999999999999986, 59.999999999999986),
(17.500000000000004, 0, 59.999999999999986),
(17.5, -59.999999999999979, 59.999999999999993),
(17.500000000000004, -59.999999999999986, 0),
(17.5, -59.999999999999993, -59.999999999999979),
(17.500000000000004, 0, -59.999999999999986),
(17.5, 59.999999999999986, -60),
(17.500000000000004, 59.999999999999986, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
]
surf.weights=[
1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 6.95192e-310, 52.5, 60, 0, 52.5, 60, 60, 52.5, 3.67e-15, 60, 52.5, -60, 60, 52.5, -60, 7.35e-15, 52.5, -60, ]
surf.knotvector_u=[0, 0, 0, 1, 1, 1, 1, 1, ]
surf.knotvector_v=[0, 0, 0, 0.25, 0.25, 0.5, 0.5, 0.75, 0.75, 1, 1, 1, ]
# Evaluate surface points
surf.evaluate()
and I get below error
ZeroDivisionError Traceback (most recent call last)
Input In [83], in <cell line: 1>()
60 surf.knotvector_v=[0, 0, 0, 0.25, 0.25, 0.5, 0.5, 0.75, 0.75, 1, 1, 1, ]
61 # Evaluate surface points
---> 62 surf.evaluate()
64 # Plot the control points grid and the evaluated surface
65 surf.vis = VisMPL.VisSurface(vis_config)
File ~/anaconda3/lib/python3.9/site-packages/geomdl/BSpline.py:616, in Surface.evaluate(self, **kwargs)
613 self.reset(evalpts=True)
615 # Evaluate and cache
--> 616 self._eval_points = self._evaluator.evaluate(self.data,
617 start=(start_u, start_v),
618 stop=(stop_u, stop_v))
File ~/anaconda3/lib/python3.9/site-packages/geomdl/evaluators.py:291, in SurfaceEvaluator.evaluate(self, datadict, **kwargs)
289 knots = linalg.linspace(start[idx], stop[idx], sample_size[idx], decimals=precision)
290 spans[idx] = helpers.find_spans(degree[idx], knotvector[idx], size[idx], knots, self._span_func)
--> 291 basis[idx] = helpers.basis_functions(degree[idx], knotvector[idx], spans[idx], knots)
293 eval_points = []
294 for i in range(len(spans[0])):
File ~/anaconda3/lib/python3.9/site-packages/geomdl/helpers.py:250, in basis_functions(degree, knot_vector, spans, knots)
248 basis = []
249 for span, knot in zip(spans, knots):
--> 250 basis.append(basis_function(degree, knot_vector, span, knot))
251 return basis
File ~/anaconda3/lib/python3.9/site-packages/geomdl/helpers.py:167, in basis_function(degree, knot_vector, span, knot)
165 saved = 0.0
166 for r in range(0, j):
--> 167 temp = N[r] / (right[r + 1] + left[j - r])
168 N[r] = saved + right[r + 1] * temp
169 saved = left[j - r] * temp
ZeroDivisionError: float division by zero
The equivalent ACIS code
// spline
int degree_of_u = 2;
logical is_rational_in_u = TRUE;
int OPEN = 0;
int form_u = OPEN;
int NO_SINGULARITY_AT_U_BOUNDARY = 0;
int pole_u = NO_SINGULARITY_AT_U_BOUNDARY;
int control_points_in_u = 5;
int degree_v = 2;
logical is_rational_in_v = TRUE;
int form_v = 2;
int pole_v = NO_SINGULARITY_AT_U_BOUNDARY;
int control_points_in_v = 9;
SPAposition control_points[] = {
{52.50000000000000000, 60.00000000000000000, 0.00000000000000000 },
{52.50000000000000000, 60.00000000000000000, 60.00000000000000000 },
{52.50000000000000000, 0.00000000000000367, 60.00000000000000000 },
{52.50000000000000000, -59.99999999999998579, 60.00000000000000711 },
{52.50000000000000000, -60.00000000000000000, 0.00000000000000735 },
{52.50000000000000000, -60.00000000000000711, -59.99999999999998579},
{52.50000000000000000, -0.00000000000001102, -60.00000000000000000},
{52.50000000000000000, 60.00000000000000000, -60.00000000000002132},
{52.50000000000000000, 60.00000000000000000, 0.00000000000000000 },
{17.50000000000000355, 59.99999999999998579, 0.00000000000000000 },
{17.50000000000000000, 59.99999999999998579, 59.99999999999998579 },
{17.50000000000000355, 0.00000000000000367, 59.99999999999998579 },
{17.50000000000000000, -59.99999999999997868, 59.99999999999999289 },
{17.50000000000000355, -59.99999999999998579, 0.00000000000000735 },
{17.50000000000000000, -59.99999999999999289, -59.99999999999997868},
{17.50000000000000355, -0.00000000000001102, -59.99999999999998579},
{17.50000000000000000, 59.99999999999998579, -60.00000000000000000},
{17.50000000000000355, 59.99999999999998579, 0.00000000000000000 },
{17.50000000000000000, 0.00000000000000000, 0.00000000000000000 },
{17.50000000000000000, 0.00000000000000000, 0.00000000000000000 },
{17.50000000000000000, 0.00000000000000000, 0.00000000000000000 },
{17.50000000000000000, 0.00000000000000000, 0.00000000000000000 },
{17.50000000000000000, 0.00000000000000000, 0.00000000000000000 },
{17.50000000000000000, 0.00000000000000000, 0.00000000000000000 },
{17.50000000000000000, 0.00000000000000000, 0.00000000000000000 },
{17.50000000000000000, 0.00000000000000000, 0.00000000000000000 },
{17.50000000000000000, 0.00000000000000000, 0.00000000000000000 },
};
double weights[] = {
1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000,
0.70710678118654779, 0.50000000000000022, 0.70710678118654779, 0.50000000000000022, 0.70710678118654779, 0.50000000000000022, 0.70710678118654779, 0.50000000000000022, 0.70710678118654779,
1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000, 0.70710678118654757, 1.00000000000000000,
};
double control_points_tolerance = SPAresabs;
int num_knots_u = 6;
double knots_u[] = {
0.00000000000000000, 0.00000000000000000, 0.00000000000000000, 1.00000000000000000, 1.00000000000000000, 1.00000000000000000,
};
int num_knots_v = 12;
double knots_v[] = {
0.00000000000000000, 0.00000000000000000, 0.00000000000000000, 0.25000000000000000, 0.25000000000000000, 0.50000000000000000,
0.50000000000000000, 0.75000000000000000, 0.75000000000000000, 1.00000000000000000, 1.00000000000000000, 1.00000000000000000,
};
double knot_tol = SPAresabs;
//
bs3_surface bezier_surface = bs3_surface_from_ctrlpts(degree_of_u, is_rational_in_u, form_u, pole_u, control_points_in_u, degree_v, is_rational_in_v, form_v, pole_v, control_points_in_v, control_points, weights, control_points_tolerance, num_knots_u,
knots_u, num_knots_v, knots_v, knot_tol);
spline spl = spline(bezier_surface);
Could you please take a look at this bug ? I would greatly appreciate your assistance. Thank you in advance!
I don't have a valid ACIS license anymore, so I cannot test it. ZeroDivisionError may happen, because the algorithms are using the user input directly. There is a frange implementation, but I doubt that's the problem. There were several other problems like that and converting values like -59.99999999999998579 to -60 worked fine at that point. You could try that.
I was planning to implement a more precise floating point control to eliminate such issues, but never had time to do it without adding any additional dependencies.
I don't have a valid ACIS license anymore, so I cannot test it.
ZeroDivisionErrormay happen, because the algorithms are using the user input directly. There is afrangeimplementation, but I doubt that's the problem. There were several other problems like that and converting values like-59.99999999999998579to-60worked fine at that point. You could try that.I was planning to implement a more precise floating point control to eliminate such issues, but never had time to do it without adding any additional dependencies.
I changed this snippets to
from geomdl import BSpline
# Create a BSpline surface instance (Bezier surface)
surf = BSpline.Surface()
surf.degree_u=2
surf.degree_v=2
surf.ctrlpts_size_u=5
surf.ctrlpts_size_v=9
surf.ctrlpts=[
(52.5, 60, 0),
(52.5, 60, 60),
(52.5, 0, 60),
(52.5, -60, 60.0),
(52.5, -60, 0),
(52.5, -60.0, -60),
(52.5, 0, -60),
(52.5, 60, -60.0),
(52.5, 60, 0),
(17.5, 60, 0),
(17.5, 60, 60),
(17.5, 0, 60),
(17.5, -60, 60),
(17.5, -60, 0),
(17.5, -60, -60),
(17.5, 0, -60),
(17.5, 60, -60),
(17.5, 60, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(17.5, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
(0, 0, 0),
]
surf.weights=[
1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 0.5, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0.707107, 1, 0, 52.5, 60, 0, 52.5, 60, 60, 52.5, 0, 60, 52.5, -60, 60, 52.5, -60, 0, 52.5, -60, ]
surf.knotvector_u=[0, 0, 0, 1, 1, 1, 1, 1, ]
surf.knotvector_v=[0, 0, 0, 0.25, 0.25, 0.5, 0.5, 0.75, 0.75, 1, 1, 1, ]
# Evaluate surface points
surf.evaluate()
# Plot the control points grid and the evaluated surface
surf.vis = VisMPL.VisSurface(vis_config)
I am still encountering the same error.
Could you also update the weights like you did for the control points? I'd try converting 0.707107 to 0.70711 and remove one significant if it doesn't work.