Ray In Geometry Example

[Brittany Bhadd]

Iam able to run the DICOM example correctly with the given input files. I then tried making the voxel dimension smaller in the input files to better match the data that I plan to use. To do this I changed the x and y start positions in the g4dcm files.

Next, I changed the x and y extents to -64 to 64, while keeping 128 x 128 pixels, representing a voxel size of 1 mm x 1 mm x 5 mm. The example does not run to completion. I have multiple warnings about track stuck as shown below.

Thank you for the response. Is there a setting that will improve precision or is it better to combine voxels to be larger? The job hangs in the middle of an event and does not complete. Here is a portion of screen output just before the job hangs:

This problem has been perplexing me because in the past I know we have worked with smaller voxels and the AAPM Task Group 195 Monte Carlo Benchmarking report has an example with 1 mm^3 voxels that we previously used as a benchmark. I think I have figured out the issue. In the past we used the Nested Parameterisation, and this seems to work fine for small voxels. This is what was used for the TG 195 report as well. The example I described above works fine for small voxels when the Nested Parameterisation environment variable is set. Thank you for your help.

Prof. Acre,

Hi, I have used your solution in my small voxel DICOM(0.97656250.97656253mm). However, there will be a wrong dose depoited when the direciton of primary particles is negative. The first one or two layer will have much more dose while the interface of patient have nearly 0 Gy. Could you please tell me some ideas to solve the problem? I will appreciate it sincerely!

Best wishes

Hi all,

I was having the same issue with DICOM/Parameterised voxel geometries, where the simulation got stuck on certain events depending on the set seed, and implemented the change suggested. In doing so I came across this in G4Navigator.cc (v11-1-p2):

For my purposes (medical research), simply abandoning an event is better than having the simulation get stuck for a long time, especially when running on a cluster with specified user runtime. Is there a G4 internal reason the overlap check needs to be performed automatically at this point?

100+ GeometryByExample problem sets have been drafted based on misconceptions identified in the research literature and by geometry teachers. Each assignment is aligned to geometry standards and includes both correct and incorrect worked examples accompanied by prompts to help students to analyze and explain core geometry concepts.

I'm currently working through Frenkel's beautiful paper: _cache/hep-th/pdf/0512/0512172v1.pdf. I'm looking for a good example of a projective curve to get my hands dirty, and go through the general constructions that Frenkel shows there and try to do them manually for this example of a curve. Are there any good instructive examples for doing this? (Or does it always get out of hand very quickly?)

Unfortunately I don't think geometric Langlands is very easy on any curve.The only curve where the objects are readily accessible is $P^1$, but even there the general statement is kind of tricky (see Lafforgue's note here). I would look at Frenkel's writings on the Gaudin model, which is a concrete illustration of the Beilinson-Drinfeld-Feigin-Frenkel approach to geometric Langlands for $P^1$ with several punctures. Also Arinkin and Lysenko worked out explicitly a case of geometric Langlands (in a stronger sense) on $P^1$ minus 4 points -- see the first four papers on a mathscinet search for Arinkin. So the answer is try $P^1$ with some punctures, but don't be surprised if things are rather tricky already there.

Our answer - $P^1$ with nodes and cusps (and more general singularities) are very good examples for doing this. The answer is actually motivated by Serre's "Algebraic groups and algebraic class fields ..." where he works with generalized Jacobions and abelian Langlands (i.e. class field theory).

2) At the same time it gives the GL-oper explicitly (moreover it gives "universal" GL-opermeaning that its coefficents are quantum Hitchin (Gaudin) hamiltonians, but not complex numbers). Fixing values of Hitchin's hamiltonians we get complex-valued GL-oper, which corresponds by Langlands to these Hitchin's hamiltonians. So the Langlands correspondence: Hitchin D-module -> GL-oper is made very explicit.

To some extent this solves the questions about the Laglands for GL-Hitchin's system.We have not write down the proof of "Hecke-eigenvaluedness" of Hitchin's D-modules.But it seems that is rather clear(may be not the ritht word), if you take appropriate point of viewon Hecke's transformations - as in the paper by A. Braverman, R. Bezrukavnikov Langlands correspondence for D-modules in prime characteristic: the GL(n) case

One of key ideas - that you can do everything in "classical limit" and than quantize.They worked for finite fields - so they can use some trick to go from classical to quantum,over complex numbers we have explicit formulas by Talalaev so they should do the same.

It would be very nice project to consider from this point of view $P^1$ with cusp,the cotangent to moduli space of vector bundles is $[X,Y]=0/GL(n)$,the same thing which is considered in Etingof's Ginzburg's paper

In our paper -th/0303069 we described classical Hitchin system for the degenerate genus 2 curvey^2 = (x-a)^3 (x-b)^3. However we did not check that our "analogs" of Narasimhan-Ramanan coordinates are indeed limits of true Narashimhan-Ramanan coordinates, so it might not be very helpful. Also Talalaev's formula cannot be applied directly for the Lax matrix in these coordinates. It is coordinate dependent, it is solvable problem but requires some work.

and returned the area units in what you want, accounting for the projection that your data need to be in. If you try to do this through an update or other cursor, you will have to account for the projection as well as the unit change.

Python expressions can use the geometry area and length properties with an areal or linear unit to convert the value to a different unit of measure (for example, !shape.length@kilometers!). If the data is stored in a geographic coordinate system and a linear unit is supplied (for example, miles), the length will be calculated using a geodesic algorithm. Using areal units on geographic data will yield questionable results as decimal degrees are not consistent across the globe.

The most important thing to notice is that our ExampleTriangleGeometry class inherits from QQuick3DGeometry and that we call the QML_NAMED_ELEMENT(ExampleTriangleGeometry) macro, making our class accessible in QML. There are also a few properties defined through the Q_PROPERTY macro which are automatically exposed in our QML object. Now, let's look at the QML Model:

Now, lets look at the other important part of the C++ code, namely the updateData() method. This method creates and uploads the data for our custom geometry whenever a ExampleTriangleGeometry class is created or any of its QML properties are updated.

Then the vertex data is uploaded and the stride is set by calling setVertexData() and setStride(). The bounds of the geometry is set by calling setBounds. Although not used in this example setting the bounds is needed for shadows to work. Then the primitive type is set by calling setPrimitiveType(). Lastly, we specify how the attributes for position, normal and uv coords are laid out in memory in the previously uploaded buffer by calling addAttribute() for each attribute.

Does anyone remember an example file that was shown that took a basic pipe and some blocks in the shape of a handle and used remeshing and smoothing to make a more complex surface blend? I keep searching for this and keep coming up empty handed.

rhino example19201440 73.6 KB

here is a rough sketch that I did as I remember it. I think it was a one page website that talked about taking blocks of geometry to make the overall shape you wanted. Then using tri-remensh to combine and smooth the geometry. and once that was done you were able to use the new quad remensh to go back to surfaces.

Appreciate the help but no special treatment needed here. I can work though getting this process to work for me. Just wanted to find the page that I keep thinking about to see if there was something I was missing.

I am a concept modeler and would just be using the process to create artistic geometry and general representations of geometry. I also work closely with a group of poly modelers so just sharing process with the team. this workflow can quickly generate more complex geometry with basic input.

I did not realize that in your first post, sorry. My personal lazy preferred way would be to create the flaps on the side of your box in their unfolded state, and join all naked edges so you end up with the brep topology you are looking for, just in a different geometry. You can then fold/unfold it from there.

But I imagine there is a more complex case you are working on that you are not showing here, where this method would not work. In that case JoinEdges or CreateFromJoinedEdges is probably the way to go as you say.

To get these edge indices, you can loop through the edges of the Brep until you find one that looks like the one you want to join. For example, from the edge that was picked, you can get the vertices at each end (in the panel brep), find the corresponding vertices in the flange brep, and then find the edge of panel that goes between these two vertices.

Brep.CreateFromJoinedEdges creates a brand new object, so I have to delete original brep if I want to emulate JoinEdge command. Correct? Is there a way to avoid it and make new brep inherit properties of the original to truly emulate JoinEdge command?

Geometry is the branch of mathematics that relates the principles covering distances, angles, patterns, areas, and volumes. All the visually and spatially related concepts are categorized under geometry. There are three types of geometry:

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