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when to normalize data [closed]

asked 2020-04-12 11:49:53 -0500

superfly gravatar image

updated 2020-04-12 11:52:54 -0500

Regarding raw image data in opencv at what point am I supposed to normalize the data? While calculating the Normal vector to a plane I get 2 answers depending on when I normalize the data e.g. right away or later. Is there a hard answer for this?

Normal line from normalized points/vectors <a,b,c> =[0, -0, -0.618409]
Normal line from raw points/vectors: <a,b,c> =[0, -0, -140756]


calculate_vector_from_points(cornerNorm1, cornerNorm2, vec12); 
calculate_vector_from_points(cornerNorm1, cornerNorm3, vec13);
vec_cross_product_2 = vec12.cross(vec13);
std::cout << "Vector 13 =" << vec13 << std::endl;
std::cout << "Vector 12 =" << vec12 << std::endl;
std::cout << "Normal line from normalized points/vectors <a,b,c> =";
std::cout << vec_cross_product_2;
Point3d raw_vec12(0, 0, 0);
Point3d raw_vec13(0, 0, 0);
calculate_vector_from_points(raw_1, raw_2, raw_vec12); 
calculate_vector_from_points(raw_1, raw_3, raw_vec13);
Point3d vec_cross_product_3 = raw_vec12.cross(raw_vec13);
std::cout << std::endl;
std::cout << "Normal line from raw points/vectors: <a,b,c> =" << vec_cross_product_3;
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Closed for the following reason duplicate question by superfly
close date 2020-04-17 14:08:44.265700

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answered 2020-04-13 01:14:20 -0500

mvuori gravatar image

One normalises data when: * one wants to convert data to a range that is easy to understand * an algorithm or a function expects data in certain range * wider range of values (and bigger data types) have been used temporarily * etc...

Of course, the conversation is most often lossy due to rounding, therefore it is best used as late as possible. And of course, different numbers given to an algorithm produce different results unless the algorithm outputs some relative result. The question is always: how is the data used next and later... ...But mathematically, the magnitude of a normal vector is 1, so it should be normalised to that magnitude, and by definition, the magnitude of the source data should not matter.

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Lets say my camera captures several dots. On these dots I calculate a few vectors. And from these vectors I get a cross product for a line normal to a plane. What point do I intercede with normalization? If I get normalization immediately after capturing the raw data do I have to do a more normal functions?

superfly gravatar imagesuperfly ( 2020-04-14 21:29:02 -0500 )edit

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Asked: 2020-04-12 11:49:53 -0500

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Last updated: Apr 13