paumard
commented
3 months ago Dear user, I tried to reproduce your problem. To do that I integrated your two files in the Null plug-in. When running gyoto on the XML file, I don't get "norm drifting" warnings but another SEVERE warning : "SEVERE: Photon::hit: too many iterations (100001 vs. 100000), break". The output image is by eye identical to the one you sent as PNG.
When ray-tracing without multithreading (so that the messages arrive in order on the terminal), I see that this message appears only for a few pixels between row number 23 and row number 32. On rows 25 and 26, I count 14 such messages (each). The dark region in the center of the disk there is 20 pixels wide. I can make an educated guess that those messages arise from photons that come too close to the horizon so that time evolution stalls there. The vicinity of the horizon is also a place where the norm could legitimately diverge (numerically). To avoid such problems, we implement a sink radius in KerrBL::isStopCondition(). You could use the same mechanism.
The "white edge" is another issue. Note that it is not filled with zeros, but with NaNs. This means that the integration worked correctly and that gyoto detects that the photon trajectory crosses the disk but that something fishy happens when computing the emission. I ran Gyoto in debug mode for a single pixel:
gyoto -T1 thindisk_hyb.xml \!thindisk_hyb_part.fits --debug --imin=1 --imax=1 --jmin=50 --jmax=50
nan appears first in this line:
DEBUG: virtual double Gyoto::Metric::Generic::SysPrimeToTdot(const double*, const double*) const: v=[0,0,-nan]
whete SysPrimeToTdot is called by Gyoto::Metric::HYB::circularVelocity.
My educated guess here is that you prescription for angular velocity is non physical at this distance (v>c?), more specifically this line must yield a division by zero or the square root of a negative number:
vel[3] = dir*sqrt(-rr * (-3. / rr / rr + 2. * pow(rr, -1.-2.* (1+3.* Ww_ -4. * Aa_ * Ww_)/(2.-3.* Aa_ + Aa_ * Ww_) ) * (1.+3.*Ww_ -4.*Aa_ * Ww_)/(2. - 3. * Aa_ + Aa_ * Ww_)))/ sqrt(2.)/rr;
Dirac666666
Dear author I'm sorry to bother you, but I have a problem that is very confusing to me. When I used my metric to draw my black hole shadow, the black hole shadow is based on the thin disk model, I found that my picture was very strange, there was a white edge, it looked like it had not been calculated, And in the process of calculation, I got a large number of severe: "norm is drifting - with norm, normref=.........". I looked at my metric a hundred times, and I still couldn't find any problem, and at the same time, I calculated the innermost stable orbital under the metric, and there is a innermost stable orbital under the parameter in my xml file. But from a theoretical analysis, it seems possible to draw a normal black hole shadow like a Schwarzschild black hole. The specific details, such as the images I get, my plugins, and the xml files , I put in the zip package. I would appreciate it if you could reply me in your busy schedule my plugin.zip