Sean, To continue with the vector discussion: Now that I understand how you propose to handle the vectors, let me ask you, how would you model the examples I proposed, that I thought were impossible to model using our vectors? Using your method did not help me find a solution to them either, so I am curious how you would do it. We certainly need something more than just axis vectors, but it would complicate the contribution calculation a lot. For convenience, find them attached in this email again.
Mario. 2017-07-26 19:02 GMT+02:00 Mario Meissner <[email protected]>: > It was, indeed, just a problem of printing. Numbers are big so it didn't > fit in %d. I used %lld now and I got acceptable results. > > After looking a bit over viewweight again, there are two concepts that I > would like to know more about. > > How does hypersampling work, and what does the variable hypersample > exactly contain? > > The region struct seems to have a line of sight value that is expressed in > percentage and is then converted to a factor. Its then multiplied together > with volume and density to obtain the final weight value. What exactly is > line of sight? > > Mario. > > > > 2017-07-26 18:14 GMT+02:00 Christopher Sean Morrison <[email protected]>: > >> >> >> On Jul 26, 2017, at 10:59 AM, Mario Meissner <[email protected]> >> wrote: >> >> Sean, >> >> Today I started modifying rtexample.c so that it simulates a ray crossing >> several regions (tried with the goblet example) and returning the mass it >> saw as it crossed each region. I assumed most stuff with predefined >> constant values for now. >> >> >> Sounds good! >> >> I wonder why the last result is negative? Segment distance seems to be >> the cause, although OutHIT dist = 10134 and InHIT dist = 10114, so my >> subtraction should be returning a positive result. Will keep working on it. >> >> >> At first glance, notice how the length and volume values are the same. >> This implies maybe a data type printing problem. What are the types of >> those variables? I suspect you need %zd or %lld instead of %d. I would >> definitely figure out what is going on there before moving on. You >> obviously need non-negative lengths. :) >> >> Cheers! >> Sean >> >> >> >> Mario. >> >> 2017-07-26 15:39 GMT+02:00 Christopher Sean Morrison <[email protected]>: >> >>> >>> I think I can follow you, but I'm not sure how to put contributions >>> together. In the blade example you seem to be taking the mean value between >>> them. I'll assume that's the case. >>> Attached goes a simple box with two vectors. Should the density at point >>> a be 5? >>> >>> >>> Let’s see. The gist of the original formula (which had a segment error >>> in the denominator, looking back) is to calculate the density contribution >>> from VA, the density contribution of VB, and then take their average (i.e., >>> assume simple linear contributions from each). Simple looking at your >>> gridding without any equations, we can see that: >>> >>> contrib(a, VA) is 3.5 >>> contrib(b, VB) is 6.5 >>> >>> Adding them up and taking the average is thus density 5. So yes. ;) >>> >>> Likewise, would point b have a density of 6 then? >>> >>> >>> Yes. 8 + 4 / 2. >>> >>> I'm not sure if I calculated the contributions correctly either, but >>> this is the way that would make the most sense to me. >>> >>> >>> I think it’s as good a starting point as any and is relatively easy to >>> implement. >>> >>> That said, note that this method does have a potential flaw in that >>> we’re treating the density contributions uniformly when in reality, they >>> should probably be weighted by distance to the vector. >>> >>> In your example, they’re equidistant, so it works out. But consider the >>> implication of box that is 100 times taller, for example. Instead of 4 x >>> 4, it’s 4 x 400. Point b should be a value far closer to 8 than 4, >>> certainly not 6. That’s a problem that can be dealt with later, but >>> something to keep in mind. >>> >>> Cheers! >>> Sean >>> >>> >>> ------------------------------------------------------------ >>> ------------------ >>> Check out the vibrant tech community on one of the world's most >>> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >>> _______________________________________________ >>> BRL-CAD Developer mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/brlcad-devel >>> >>> >> <rtexample.c> >> >> ------------------------------------------------------------ >> ------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> >> _______________________________________________ >> BRL-CAD Developer mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/brlcad-devel >> >> >> ------------------------------------------------------------ >> ------------------ >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> _______________________________________________ >> BRL-CAD Developer mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/brlcad-devel >> >> >
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