In Virtual CRASH 3 or 4, users can import aerial photographs and scale diagrams in nearly any image format, including .tif (or .tiff) format. You can find more information on importing and scaling images in Chapter 9 of the User’s Guide. When importing images from any source, remember Virtual CRASH assumes a single pixel is 1 cm x 1 cm in physical size, so in most cases, the Virtual CRASH scale tool is needed to set the scale between two reference points that are visible in the photo or diagram.
The path animation tool is a great way to create fast visual aids for your case without the need to optimize a simulation scenario. Using the path animation feature, vehicles paths and kinematic sequences are predetermined without using the time-forward kinetic simulator. In this post, we’ll review some of the features and functionality of the path animation tool.
In this blog post, we discuss the simulation of test “MEA12” from this series. In this test, a 1980 Datsun 200 SX with initial speed of 15.6 m/s impacts a 1989 Chevrolet Sprint with initial speed of 6.7 m/s. The collision occurs in a 90-degree t-bone configuration. A depiction of the test is shown below.
The study of motion and of physical concepts such as force and mass is called dynamics. The part of dynamics that describes motion without regard to its causes is called kinematics . Occupant kinematics is the study of kinematics as it applies to occupants within a motor vehicle. Broadly speaking, in accident reconstruction, one uses concepts of occupant kinematics to understand mechanisms of injury causation by identifying potential points of contact between an occupant’s body and the occupant cabin itself.
With the November 25, 2017 auto-update, Virtual CRASH 4 users will be able to create 360 degree videos and Virtual Reality videos. Virtual CRASH 4 users will also have more video output options available. As always, these updates are provided to Virtual CRASH users for free!
Collision physics in Virtual CRASH is based on rigid body dynamics. In particular, most vehicle versus vehicle impacts in Virtual CRASH are simulated using the Kudlich-Slibar impulse-momentum model. This model dates back to the 1960s [1, 2] and is the basis for other vehicle collision simulators used for accident reconstruction [3, 4]. Rigid body dynamics simulators are based on Newton Laws. Newton’s 3rd Law in particular, of course, leads to momentum conservation.
In our Blog post from last year (http://www.vcrashusa.com/blog/2016/6/6/adding-traffic-signal-symbols-to-animations), we discussed how to create 2-D traffic signal symbols in your simulation environment. At the bottom of that post, we also discussed how to add semaphore objects (3D traffic signal lights) in your environment. The semaphore object has undergone significant improvements in Virtual CRASH 4 which have been made available in the October 10, 2017 update.
In both Virtual CRASH 3 and Virtual CRASH 4, the kinematics tool can be a quick and easy way to control complex pre-crash motion involving inherently unstable systems such as motorcycle or bicycle + rider systems. It also allows the user to set up a simulation at the moment-of-impact, and kinematically propagate vehicles to the point-of-impact without the needed of fine-tuning steering and acceleration inputs.
Virtual CRASH can be used to reconstruct motorcycle impact cases quickly and easily. In this blog post we will use Virtual CRASH to reconstruct “Case Study 1” presented in “Linear and Rotational Motion Analysis in Traffic Crash Reconstruction” by Keifer, Conte, and Reckamp.
Because impulses are only exchanged upon overlap of the vehicle polygon meshes, cases where you want to simulate directly wheel contact may require a little more work; remember, the wheels in Virtual CRASH are not part of the vehicle polygon mesh, and so are not considered by the collision detection algorithm. One technique to solve this problem is to directly install rigid body wheels, which is shown in the Knowledge Base post here. Another technique involves simply modifying the polygon mesh of your vehicle. This is shown below.
In Virtual CRASH you can create complex road geometries using the plane object. In this post, we will create a highway interchange ramp.
In this latest installment, we continue with our exploration of the Research Input for Computer Simulation of Automobile Collisions (RICSAC) test series. These tests make excellent benchmarks with which to study just how quickly and accurately Virtual CRASH can reproduce accident cases.
In Chapter 12 of the User's Guide, you are walked through the workflow of a typical accident reconstruction analysis involving a t-bone style impact based on a staged collision test from the Research Input for Computer Simulation of Automobile Collisions (RICSAC) series. In that case, using knowledge of the pre-impact orientations and post-impact rest positions and orientations, as well as the post-impact trajectories, we were able to iteratively converge on a reasonable solution for the collision, obtaining estimates of the pre-impact speeds. In this post, we will repeat this same process for the second RICSAC collision ("RICSAC 2").
In this blog post, we will discuss how to create custom sky modifications. In particular, we will focus on creating (1) an all-white sky and environment, (2) an all-black sky, and (3) a sky with stationary cloud effects.
Are you a die-hard fan of FARO (formerly ARAS) Reality or FARO HD, but wish there was a way to create your animations using a true 3D physics simulation tool like Virtual CRASH 3? If so, this post is for you. Here we demonstrate just how easy it is to extract the 3D simulation data from Virtual CRASH 3 and use it to define an animation path within FARO HD. In Part 1 we discussed using Virtual CRASH 3 data to animate a rollover accident. This was a more complex task due to the fact that FARO Reality/HD define the vehicle reference point at ground level, meaning we have to perform some coordinate transformations before using the Virtual CRASH 3 data; however, in simple collisions this won't be necessary, as long as there is not an excessive amount of yaw, pitch, or roll. Below we outline the simplified process for importing Virtual CRASH 3 data.
Are you a die-hard fan of FARO (formely ARAS) Reality or FARO HD, but wish there was a way to create your animations using a true 3D physics simulation tool like Virtual CRASH 3? If so, this post is for you. Here we demonstrate just how easy it is to extract the 3D simulation data from Virtual CRASH 3 and use it to define an animation path within FARO Reality.
In Virtual Crash you have the ability to take solid objects (.3ds, .dxf), separate out components, and add joints to manipulate movement. In this post, we will look at using a hinge joint to create a rotating assembly.
In a previous post, techniques were discussed concerning how to modify the different “Element” portions of a vehicle to suit your needs, but here we will discuss how to modify the “Faces” portion to get an even more custom look for your vehicle.
One of the gems of Virtual CRASH 3 is the “auto-driver” system. This feature allows the user select the paths on which the simulated vehicles are to drive (within the limits of physics of course). This is an excellent alternative to specifying the steering angles "by hand," especially for complex roadway geometries (although Virtual CRASH 3’s fast control icons are particularly handy for that purpose). In this post, we discus how to use the auto-driver system in Virtual CRASH 3.
There are nearly 400 unique vehicle meshes in the Virtual CRASH library (see the Vehicle's & Objects List); still, occasionally one has to go shopping on third-party vehicle model vendor sites to find the perfect match for a subject vehicle. Of course, one of the amazing features of Virtual CRASH 3 is the ability to import vehicle meshes in .3ds or .dxf format, and use them for your simulated vehicle models. Once a third-party mesh is imported, the final vehicle can be saved as a .vc3 file, and used in future cases. This ability to expand one’s own personal vehicle library is just one of the many amazing features of Virtual CRASH. This process is explained in the User's Guide, which can be found on the vCRASH Academy page.
So, let’s suppose you went shopping and found a great model that matches the subject vehicle in your case. You import the vehicle into Virtual CRASH, and suddenly you notice that your computer is running significantly slower, and Virtual CRASH seems to be barely puttering along. What’s going on here? The likely issue is related to the number of polygons within the imported vehicle mesh. The mesh makes up the geometrical detail of the vehicle itself. With each additional polygon, your system resources have to work that much harder to do all of the various calculations that make Virtual CRASH tick. Whether it’s a vehicle mesh or terrain mesh, one must, if possible, try to be reasonable, and manage the polygon count of imported meshes to maintain good system performance speed, otherwise simulation run time can increase, and workflow will slow. In this post, we will review how to deal with imported meshes with large polygon counts.