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Messages - Richard O'Konski

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PyroSim / Re: Can not create TSV file for screenshots!
« on: October 09, 2018, 01:41:11 pm »
The tsv file must specify one of views listed under the "Views" node in the navigation view.  It cannot name one of the built-in views - Top, Front, Side, unless you've created your own view with one of these names. To fix this, open your results and add a new view called "Top". Then your tsv file should work.

PyroSim / Re: Recommended Specs for PyroSim?
« on: May 04, 2018, 11:46:31 am »
It depends a lot on the types of simulations you will run, such as the number of cells you want in your model, what you hope to visualize, your budget, etc. Generally, I would recommend the following:

- A fast CPU. In our experience, it's better to get a processor with high clock speeds per core rather than lots of cores. We like to use Intel i7s in our office.
- A discrete mid- to high-range gaming GPU. Nvidia Geforce and AMD Radeon cards will do great. Integrated Intel is getting better but still lags pretty far behind. Generally I like Nvidia, but if you will need to use remote desktop to log into this computer, I would recommend AMD or Intel over Nvidia, as Nvidia doesn't support OpenGL over remote desktop. If you really want to use Nvidia and remote log-in to this PC, you'll either need a Quadro card ($$$) or use VNC software instead of remote desktop.
- At least 16 GB RAM.
- An SSD hard drive with at least 500 GB space or a fast HDD.

PyroSim / Re: 3D CAD import
« on: May 19, 2016, 09:35:22 am »

When PyroSim imports objects from CAD files, it imports them either as lines (for 2D CAD) or collections of triangles (for 3D CAD).  PyroSim does not convert any imported object into a high-level object type, such as a wall or slab.  Because of this, there is no way to set a wall thickness or height on the imported objects. You can, however, move or scale the objects.


Pathfinder / Re: Importing huge Revit files into Pathfinder
« on: August 24, 2015, 01:59:16 pm »
I'm also surprised by the memory issue you encountered in Pathfinder. Both PyroSim and Pathfinder use the same code and data structures to import/store the data. When I test here in the office with large DWG files, Pathfinder actually uses a little less memory that PyroSim. Unfortunately, there's not much we can do to debug the problem without the file that's giving you trouble.

The circuitous approach to making the DWG is actually the only way to import textures from a Revit model into Pathfinder or PyroSim, and it's the approach we used for our stadium model.  Autodesk (the owner of Revit and AutoCAD) is very unfriendly to third party software when it comes to texture and material information. When you export a Revit model directly to a DWG, Revit excludes the texture information. If you export a Revit model to an FBX, it contains texture information, but this information is only readable by Autodesk products, which requires you to import it into AutoCAD and then save it as a DWG. 

We are currently working on a way to streamline this process by importing FBX files directly into our software, but as I said, Revit stores the texture information in a proprietary format, which means that their FBX files wouldn't be any good for PyroSim and Pathfinder. Fortunately there is a commercial third-party plugin you can buy for Revit that would export a more friendly FBX that we will be able to import into our products, textures and all. We're hoping to include the FBX support by the end of the year.

PyroSim / Re: ventilation control
« on: December 15, 2014, 09:07:29 am »
To make a supply or exhaust, one of the vent nodes needs to be changed to an "Ambient Endpoint" node. The flow direction in the ducts then controls whether the remaining vent node will become a supply or exhaust vent.

PyroSim / Re: ventilation control
« on: December 10, 2014, 10:25:41 am »
Yes, you can model this using PyroSim.

Here is what you will need:
1) A heat detector that activates at 80 C.
2) Two HVAC Fan definitions. One fan will have a speed of 5 m^3/s and the other will have a speed of 10 m^3/s.
3) Three nodes and two ducts connecting the nodes in series. Each duct refers to a different fan.
4) The duct that points to the 5 m^3/s fan specifies an activation control that deactivates when the heat detector trips.
5) The duct that points to the 10 m^3/s fan specifies an activation control that activates when the heat detector trips.

I've attached a simple model that shows how to do this. The only difference is that the fans have a lower speed (1 and 2 m^3/s) and the heat detector trips at a lower temperature. There is also a device that monitors the duct flow. You should see that the flow quickly ramps up to 1 m^3/s until about 5 s. Then it drops to zero and ramps back up to 2 m^3/s.
NOTE: This model was made using PyroSim 2014.4.1208, which you will need to open it.

Pathfinder / Re: Dealing with large file
« on: October 13, 2014, 08:40:01 am »
There are a couple good practices that you can use while building your model to make it easier to work with:

1) Like Dave said, delete any imported geometry that isn't necessary - Revit creates very detailed objects and we don't have a way to control that yet.
2) For anything that's left over, hide as much as you can. Anything that is hidden will still show up in the results. Of course, your results may still be difficult to navigate, but you can always use offline rendering to create smoothly animated movies.
3) Setup viewpoints to quickly move about your model.

There are also a few things you can try to improve performance. Here they are in order of effort involved (least effort at the top):

1) If you have an NVidia or AMD (formerly ATI) graphics card, in Pathfinder, go to "Edit->Preferences..." and make sure that "Use Vertex Buffers" is turned on and "Animate Characters in Hardware" is selected. These are the defaults with these graphics cards, but if you ever ran Safe model it would have turned these options off.
2) Make sure you have the latest video drivers for your graphics card.
3) In Revit, make sure you have the "Detail Level" set to "Coarse" and try re-exporting your model and re-importing into Pathfinder (I personally haven't had much luck with this option, but it's worth a try).
4) From Revit, try exporting to an FBX file and in the export dialog make sure "Use LOD" is selected. You'll then have to convert the FBX file to a DWG file using AutoCAD (NOTE: this is currently the only way to get textures as well - we hope to have direct support for importing FBX files in the near future).

Pathfinder / Re: Extracting 2D Floors slowly
« on: August 07, 2014, 10:58:44 am »
Floor extraction can be a bit slow in some models, especially in 2D.  Our current algorithm is only single-threaded, which is why your CPU usage appears low (your processor has hyper-threading, which makes it appear to Windows as having 8 cores, and this algorithm only uses 1, which makes it look like Pathfinder is only running at 12% CPU usage).

Your best bet is to remove all extraneous imported lines before performing the extraction, even if the lines are in a part of the model far from where you are extracting. For example, remove all hatches, electrical, duct-work, doors, etc.  These lines are often grouped together. One trick to quickly remove many of these lines at once is to ALT-click one of the lines in the 3D/2D view, which will select its parent group.

If you still find that extraction is taking unbearably long, you can send the model to us at, and we can see if there are any other suggestions we can make based on your specific model.

In the next year I hope to finish a side-project I've been working on that will vastly improve extraction speed. Right now we have some other features that are taking priority.

Pathfinder / Re: Calculate comfort distance <-> p/m²?
« on: June 05, 2014, 08:15:59 am »
The comfort distance is implemented as shown in Figure 2 of your image.  Each occupant is programmed to be autonomous, which means that he/she has no knowledge of the other occupant's comfort distance as would be needed in Figure 1, since each occupant can have a different comfort distance. 

In addition, my earlier description of the comfort distance may be a bit misleading.  Occupants don't actually try to maintain this distance away from walls/occupants. Instead, as an occupant is moving, they calculate intersections with other occupants/walls along their path. If they sense that they will hit the other occupant/wall within this distance, they stop.  This means that one occupant can be travelling directly behind another occupant at the same speed and within a distance smaller than the comfort distance because they will not detect that they will hit one another. The same is true for walls. The occupant can travel right alongside a wall because they won't detect an intersection with that wall. This is a feature we hope to improve in the future.

Pathfinder / Re: Calculate comfort distance <-> p/m²?
« on: June 04, 2014, 08:17:55 am »

You have interpreted the formula correctly. You will most likely need to use a lower value for comfort distance than the calculated value to achieve your desired density. For instance, after trial and error I came up with the value of .08 for comfort distance to achieve 3 pers/m2.

I'm not quite sure I understand your second question.  The comfort distance is the distance an occupant tries to maintain between his/her body and another occupant's body.  Figure 9 in the technical manual is illustrating two different configurations in which occupant's might have conflicting paths and is not necessarily related to comfort distance.

If you want to learn more about how the comfort distance affects decision making, see the section, "Avoid Occupants", of the technical manual.

Pathfinder / Re: Calculate comfort distance <-> p/m²?
« on: June 03, 2014, 11:02:27 am »

The way you would affect the density in Pathfinder would be to set the comfort distance between occupants (Model->Edit Profiles...->Advanced). We do not currently have a formula that describes the relationship between comfort distance and density, however, which means you will need to do some trial and error, but you could use this to find almost any density.

After performing the following steps, I came up with a comfort distance of .08 m to achieve a density of 3 persons/m2:
  • Open the attached model in Pathfinder 2014.
  • Calculate an upper bound on the comfort distance using the following formula:
    C=1.422/D.5 - W
    where C is the comfort distance, D is your required density, and W is the shoulder width of an occupant. This formula assumes that occupants arrange themselves in a tight pattern (sphere packing). Occupants in Pathfinder don't actually pack this tightly, but this will give you an upper bound on the comfort distance.
  • Set this as the comfort distance for the default occupant profile.
  • Run the simulation.
  • View Room Usage Results (Results->View Room Usage...)
  • Uncheck the box next to "Remaining (Total)" and check the box next to "Floor 0.0 m->Room00".
  • Take the peek number of occupants and divide it by 100 (the area of that room).
  • If this doesn't match the required density, adjust the comfort distance and repeat steps 4-8.

PyroSim / Re: Export Maya file to PYROSIM as .STL
« on: May 07, 2014, 10:46:49 am »
I don't have much experience with Maya, but it looks like it will export to the DWG file format (,topicNumber=d30e33712), which would probably work much better with PyroSim than STL. 

STL is geared more toward single, simpler objects or objects that must be represented in PyroSim as solids.  DWG is better for complex scenes with many objects.  DWG also supports colors and textures, which STL does not (though I'm not sure if Maya itself will export colors/textures to a DWG).

Please let us know if you have any other questions.

Richard O'Konski
Thunderhead Engineering

PyroSim / Re: Convert cad lines into walls
« on: January 17, 2014, 09:36:15 am »
After you've converted the lines into walls, the resulting walls should be selected. You can edit the height in the object properties. To do so, perform these steps:

  • Right-click the resulting wall(s) either from the Model View (the main 3D/2D view) or the Navigation View (the tree on the left).
  • Select Properties... from the right-click menu.
  • Go to the Geometry tab.
  • Enter the new height in the Height field.

Richard O'Konski
Thunderhead Engineering

PyroSim / Re: Importation of .STL in PyroSim
« on: May 13, 2013, 08:50:18 am »
Our STL reader is perhaps a bit too strict, but if you change delete "STL" on the first line, it should work.

Richard O'Konski
Thunderhead Engineering

PyroSim / Re: Import cad files with different floors
« on: May 29, 2012, 10:07:55 am »
PyroSim actually does allow multiple DXF/DWG imports in the same model.  After importing, you may need to reset the view (Ctrl+r) to see your geometry.  If you still can't see your geometry after resetting the view, contact Thunderhead at so we can help you debug the problem. 

Like AndrewG said, if each import file defines the data at the same Z location, you'll need to offset the geometry along Z in PyroSim.  This can be done by right-clicking the import group in the navigation view and select Copy/Move....

Richard O'Konski

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