New Terminal Behavior Action Types

Posted on September 27th, 2021

Pathfinder 2021.3 introduced Attractors, a tool for providing awareness-based detours. In order to achieve this new Behavior, additional action types were needed. In total, there are 3 new terminal step types, which are behavior actions which can be used as the final action in a behavior. In addition to Goto Refuge Rooms and Goto Exits, the following actions may now be used. … Read More

Improvements in Pathfinder 2021.3

Posted on September 1st, 2021

Pathfinder 2021.3 focuses on improving multi-project management and improving dynamic occupant behavior for advanced applications. Additionally, this Pathfinder release is supported by Results improvements which incorporate technology advancements in video rendering. … Read More

Attractors Preview for Pathfinder 2021.3

Posted on August 6th, 2021

Restrooms modeled with Attractors in Pathfinder 2021.3.
Occupants in a waiting room utilize the nearby restrooms as needed via the new Attractors feature.

Pathfinder 2021.3 introduces Attractors as a brand new way to allow occupants to interact with objectives outside of their main behavior. Perhaps some airline passengers are tempted by a cafe on their way to their gate, museum attendees are swayed to visit the gift shop, or subway commuters have a few spare minutes to use the restroom before their departure. In each of these scenarios, there is some percentage of the population which will be attracted to a secondary objective. … Read More

2021.2 Patch Release – Available Now

Posted on May 26th, 2021

One of our Reseller Partners identified an issue when dragging items in the navigation view. When this happens, the application freezes and requires a forced shutdown to proceed. This issue was introduced in the 2021.2.0512 release of both PyroSim and Pathfinder. 

We have identified the problem, and have uploaded patch releases that addresses the bug. The updated versions of PyroSim and Pathfinder are available now.

… Read More

Improvements in Pathfinder 2021.2

Posted on May 10th, 2021

Pathfinder 2021.2 introduces queueing as a new behavior which can greatly expand modeling options and capabilities. New user interface enhancements make it quicker than ever to find objects and edit properties.
… Read More

Proximity Analysis and the Thunderhead development process

Posted on April 29th, 2021

The upcoming release of Pathfinder Results version 2021.2 will include a Proximity Analysis feature based on the paper EXPOSED: An occupant exposure model for confined spaces to retrofit crowd models during a pandemic by Enrico Ronchi and Ruggiero Lovreglio. In the paper Enrico and Ruggiero lay out a method to create metrics that measure occupant exposure in microscopic scale environments, which enables evaluation of the efficacy of infection mitigation measures. In simpler terms, they supply a way to measure how effective social distancing measures are at preventing the spread of disease. This post will lay out our development process to create this and other features and summarize the proximity analysis feature as implemented in version 2021.2.

The Thunderhead development process

At Thunderhead Engineering, we have periods of time that we call “Project Phoenix” where developers can work on any project that is interesting to them, whether it is a marketable feature or just a fun research project. During our Project Phoenix iteration last June, two of our interns worked on a project involving tracking the spread of an infectious disease in a Pathfinder model. This initial project modified the Pathfinder simulator to produce a simple SIR-like model during occupant movement.

After this project was completed, our team discovered Enrico and Ruggiero’s paper. After speaking with Enrico and showing him their prior project, our interns and the rest of the development team decided to modify the project to reflect the paper’s suggestions and implement it as a new feature in our Results viewer. After 3 iterations of the project, and some help from the rest of our development team, the proximity analysis feature is ready for release.

What is Proximity Analysis?

Unlike the first iteration of the project, the Proximity Analysis feature shipping in the upcoming 2021.2 release does not modify the Pathfinder simulator. Instead, it post-processes the output of Pathfinder simulations in our Results program. The Results Viewer generates a proximity analysis report that provides various metrics regarding occupant exposure, including the amount of time that k number of occupants are within a proximity radius of another occupant, how many occupants are violating the proximity radius at any given point in time, and a global exposure time metric. Because this feature is part of Results viewer and does not modify the simulator, users will not need to re-create or re-run simulations to generate Proximity Analysis reports. They can be generated using the results from any existing Pathfinder simulation.

Example Proximity Tracing Graph
Example of one of the graphs output by the new Proximity Analysis feature of Pathfinder Results 2021.2

How would Proximity Analysis be used?

One case where proximity analysis is particularly useful is when evaluating social distancing measures. By performing a baseline/control simulation, changes made to the Pathfinder model can be evaluated by their effects on the global occupant exposure metric to determine if the changes are effective in enforcing social distancing. This can also be used to compare different social distancing measures against each other to determine which ones are the most effective.


Our team enjoyed creating this new Proximity Analysis feature, and we look forward to continuing to improve our products. You will be able to access Proximity Analysis in the upcoming 2021.2 release. If you have any suggestions for features you would like to see in our products, you can email them to our Support team at and we will consider them.


Ronchi, Enrico, and Ruggiero Lovreglio. “EXPOSED: An Occupant Exposure Model for Confined Spaces to Retrofit Crowd Models during a Pandemic.” Safety Science, vol. 130, Oct. 2020, p. 104834.,

Queues in Pathfinder 2021.2

Posted on April 23rd, 2021

Queues introduce an entirely new concept of occupant movement to Pathfinder which is restricted by pre-determined Paths and waypoints called Services. This will allow users to better simulate behaviors at airports, restaurants, amusement parks, and more. … Read More

User Experience Improvements to Pathfinder 2021.1

Posted on February 23rd, 2021

Pathfinder will also benefit from feedback from our users. This release focuses on incorporating their suggestions in to our products to improve the user experience. We have made several usability improvements to Pathfinder in the 2021.1 release, some of which are mentioned below.

Update: The 2021.1 Pathfinder Release is available now

Added copy/paste functionality to Occupant Profiles

Expanding upon the functionality that we added to copy and paste geometry in Pathfinder 2020.1, we added the ability to copy and paste Occupant Profiles between separate Pathfinder instances. This means that users will no longer have to re-define the same profile in separate models, and can instead copy the profiles from one model to another. This is especially useful if users have several different profiles that are commonly used across a large number of models.

Added as-you-go undo/redo support for the Add a Polygonal Room tool

Similar to the changes to the wall and slab tools that we mentioned in our post about User Experience Improvements to PyroSim in 2021.1, we have added as-you-go undo/redo support for the add a Polygonal Room Tool.

Now, if a user makes a mistake when drawing a complex room shape, they will no longer have to start drawing that room from the beginning. They will have the ability to undo/redo any of the points they have drawn. This is especially useful for users that commonly draw their Pathfinder models on top of a 2D floorplan. You can see a short gif of this feature below.

Enhanced Monte Carlo user manual now available under the “help” menu

The Monte Carlo utility packaged with Pathfinder can help create models with randomized occupant positions and properties. This allows users to create multiple randomized copies of a model, run them sequentially, and process the resulting data set for research or regulatory requirements. The User Manual for our Monte Carlo command line utility is now available both online and in the application help menu.

Scripted Screenshots

We recently added the ability for users to interact with the Results viewer of both Pathfinder and PyroSim to generate a series of screenshots based on views that are defined in the Results view. This is particularly for users that generate reports from a series of commonly used views, as it removes the tedium of manually creating these screenshots in the Results UI. You can read more about this feature in Section 2.16.4 of the Results User Manual.

Monte Carlo Improvements in Pathfinder 2020.5

Posted on November 13th, 2020

Since Pathfinder 2018.3, users have been able to take advantage of Monte Carlo simulations through a command line interface. In modeling, the Monte Carlo method is used to randomize inputs across many simulation instances. With a statistical analysis applied, users can create probablistic interpretations of the resulting data sets. It is often used in research and is also required by regulations such as RiMEA. … Read More

Mars Colony Biome Evacuation Analysis by Szymon Matkowski

Posted on August 11th, 2020

Our support team has been assisting Szymon Matkowski with his recent project based on a feasibility study, completed by a team at Wroclaw University of Science and Technology, of possible layouts and technical solutions for a theoretical base on Mars. The study was part of a competition sponsored by The Mars Society in which the team at Wroclaw won second place. In Matkowski’s study, he analyzes evacuation of a Mars colony biome under threat of decompression or fire.

Diagram of Twardowski Colony Biome Evacuation
An overview of Matkowski’s evacuation plan based upon the Wroclaw team’s design.

Safety of the people is a top technical priority in every building or device – in any place. All: structure, MEP systems and the layout should be focused on minimizing the risk of life loss. Design of a base, or colony on other planet also should comply with this principle. The layout of all safety egress communication (passages, corridors, staircases, lifts etc.) should not be changed or altered. The unchangeable layout of those elements is a bone system for the functional layout and all the decoration we see. The drawback of such solution is that – once designed the layout is frozen. Any change leads to re-examination of all safety measures – which is very expensive (even in Earth’s conditions). One of the most important coefficients is evacuation time. Time – which people have to save their lives. This blog entry describes my research on Evacuation movement speed on Mars and a sample evacuation time count. Depending on the threat (decompression, fire and smoke) additional means should be provided : smoke exhaust, additional air supply, sealed safety rooms, emergency teams access routes and action plan. For the purpose of the investigation I have used a fragment of Twardowsky Mars Colony. Twardowsky won 2nd prize in 2019 competition organized by Mars Society. You may see the presentation here. Also the competition entry of the Base was published in a book.

During Matkowski’s analysis, which he completed in less than two months as his first Pathfinder project, many challenges were addressed. This included approximating the speed adjustment with Mars gravity and with various space suit equipment, behavior adjustment upon triggering events such as decompression, and the simulation of airlocks with pressurization phases. The Thunderhead Engineering support team aided Matkowski throughout these challenges which led to his successful analysis.

You can read Matkowski’s full analysis for free on the website.