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As a software engineer, just writing that line brings my heart rate up. HLA in particular makes things a little harder because of the sheer number of exceptions that HLA throws, even for non-exceptional reasons. In this article, we will discuss two minor additions to VR-Link 5.0.1: One that helps find the error and another that helps you recover from an error gracefully.

First things first "” finding the error. Have you ever had a crash (hopefully not too many) in VR-Forces and encountered a little dialog asking you to save a memory dump? If you send that memory dump to us, we can analyze the VR-Forces source code and find the cause of that crash. This is actually a fairly simple feature that Windows provides. To make it even easier for you, however, we now have a simplified version of this in VR-Link that you can implement in your own applications.

DtMinidump miniDump("ApplicationName"); //Enable mini-dump.

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It can take an athlete up to 18 months to return to sport after a torn ACL; even after surgical reconstruction and physical therapy, the athlete has up to a 30% chance of sustaining a second injury. Additionally, athletes have between a 50-100% chance of developing osteoarthritis within 20 years of their initial injury. Prevention of these types of injuries is key and it is especially important to know when it is safe for athletes to return to sport after such an injury.

The TEAM VR (Training Enhancement and Analysis of Movement Virtual Reality) Laboratory in the Division of Sports Medicine at Cincinnati Children’s Hospital Medical Center is leading the development of virtual environments to objectively quantify the progress of injury prevention training and physical therapy so that adolescent athletes can perform at a high level. TEAM VR has chosen VT MÄK’s DI-Guy human simulation software to help create sport-specific scenarios for training and evaluation.

TEAM VR’s virtual environments aim to give physicians, physical therapists, athletic trainers, practitioners, and strength and conditioning specialists the tools to accurately measure the biomechanics of a child athlete (joint movements, strength, or flexibility for example) by actively engaging him/her in realistic, immersive sport scenarios; these scenarios are performed in a virtual environment that mimics competition on the field/court of play. The TEAM VR laboratory is equipped to utilize virtual environments for knee injuries, as well as concussion prevention. It can also be used as an education simulation center to help sideline first responders like athletic trainers and team physicians gain experience with sideline injury scenarios.

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Among it's many other new features, VR-Link introduces generic attributes and parameters for version 5.1. Generics are a way of accessing extended information in your FOM that is not normally supported. For example, lets say your FOM, based on RPR, contains an extra attribute on entity objects called "RadarSignature." Once generics are enabled in VR-Link, all you have to do is ask for your data:

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Ever have trouble getting the gas nozzle into the tank of your car? Imagine trying to do that in mid-air where the gas station is flying and so is your car (well, airplane). Mid-flight fuel transfer is complicated by the fact that everything is in motion, the gas hose is dangling out of one plane, and the pilot has to maneuver his plane into exactly the correct position to connect. Simulating this maneuver in a networked environment is difficult because the relative
positions, velocities, and accelerations of the two aircraft have to be communicated precisely. Delays in network messages can’t be allowed to sabotage the whole operation. QuantaDyn Corporation, an engineering firm specializing in training simulations, has developed a technical solution for networked aerial refueling training, using MÄK’s VR-Link for DIS standard protocol.

The "dead reckoning" technique normally used struggles when two entities are moving so fast and so close together.  As time goes by, entities using dead reckoning compute the location of remote aircraft each frame until they receive a position update from the remote trainer. This approach avoids flooding the network with position updates every frame, but poses a dilemma for close proximity training. For example, at 275 knots an aircraft will move almost 8ft in 1/60th of a second "” the typical frame rate of the pilots visual scene. Standard dead reckoning only sends position updates when an aircraft goes outside of a certain threshold and can result in a jump of a foot or two when a new position update is received. When refueling mid-flight, those few feet can make a huge difference. Avoiding this dead reckoning gap is the main issue facing aerial refueling training.

MÄK’s VR-Link allows QuantaDyn to modify the way they use standard DIS packets without having to update the DIS interface. They are able to send relative position, velocity, and acceleration updates instead of standard position,
velocity, and acceleration updates by altering the information given to the VR-Link software and selecting an alternative dead reckoning algorithm. So instead of moving 8 feet per update relative to the world, the plane being fueled is barely moving at all relative to the tanker aircraft.  VR-Link provides the necessary "gateway" to send and receive data to and from the DIS network.

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Maybe you’ve seen the newest addition to the MÄK Product Suite: the MÄK FOM Editor. Some of you may have been surprised to see it’s a web page "” most modeling and simulation applications are heavyweight desktop applications.  MÄK is leading the industry by bringing lightweight and powerful web applications to the modeling and simulation community. For this article, I want to describe why we choose the web for the MÄK FOM Editor and discuss some of the technologies that enabled it. I will also talk briefly about security and what is happening to your data when you use it.

At home on the web

We chose to develop the MÄK FOM Editor as a web-based application because we could do it quickly with less hassle than a standard desktop application. First, we could develop it once and deploy it on any platform for which our customers had a web browser (we assume you all do). Second, since there is no heavyweight deployment process, it means we could release new versions of it "“ with bug fixes and new features "“ almost every day! While the former makes development cheap enough , the latter is really the best part. Within a day of using it, one of the first users reported a few minor problems and within hours they were resolved.

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The HLA standard makes no guarantee for how data is marshaled over the network. Under most circumstances there’s no reason for anyone to care how it’s in there as long as you have access to it. However, there is one situation where it does matter. If you need a 64-bit or 32-bit byte aligned value, HLA gives you no option to do that. And if you are casting a pointer to a 64-bit value, you need that byte alignment to access it correctly.

In the past, VR-Link has managed to get around this by simply copying all attributes from the RTI to a new byte aligned memory space to allow said casting. As you might expect, this extra copy takes processing time and will slow down your simulation some amount. Starting with the MÄK RTI 4.3, however, we have decided to force all attributes to be byte aligned to either 32 or 64 bits depending on the size of the attribute. As long as you are using the MÄK RTI, you can ask the RTI for data pointers and cast the data directly to whatever you want it to be, avoiding that copy.

Among the many performance improvements we have done in VR-Link 5.1, it now includes the option to use data pointers. And if you are using the MÄK RTI version 4.3 or better, you don’t have to do anything to turn this feature on - it will detect the right RTI version and reconfigure itself for the faster data access version. If you are using an RTI by a different vendor that includes byte alignment or you have no 64-bit values, we do provide the capability to enable the faster method by enabling ’setGetValueMethod’ in the DtExerciseConnInitializer.

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Commanders, like all good leaders, are responsible for the people below them. But they can’t do it alone. A commander’s staff exists to support the commander, work as a team, and deliver information to help make good, informed decisions. Training and preparation enable the command staff to function efficiently and properly in challenging situations; training allows the commander and his team to assess the situation, make decisions, and communicate those decisions.

Simulation plays an important role in command staff training; it’s job is to stimulate those situations where learning takes place. The simulation content depends on the echelon (level) and the missions the staff is being trained for. Marine Captains need entity-level simulation to train look-ahead surveillance for convoy protection missions while General Officers need aggregate-level simulation to model wargames for course of action analysis. (And there’s countless more examples of both.)

Modeling all of the elements needed to stimulate a command staff "” all the activity in a training scenario "” is a huge endeavor. Especially when it includes the behavior of opposing forces, the background civilian population, the political and social environment as well as the friendly force operations. To make it happen, commanders either need role players acting out the parts of each unit/entity/vehicle/person or a very powerful, believable, and capable artificial intelligence (AI) solution. Since full scale operations are time consuming and expensive to setup and run, many training tasks use the divide-and-conquer approach of focusing lessons on tasks that are manageable subsets of a complete environment. 

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If you’ve been playing with some of our VR-Link for C# examples, you might have noticed something strange. We usually include one example for each networking protocol, so you get F18DIS, F18HLA13, and F18HLA1516e.

But our C# examples do not do that. There is just a single F18Sharp executable. Don’t worry, we didn’t suddenly decide to drop all our networking standards. In C#, we have slightly changed the VR-Link interface to load all the protocol-specific material at run-time instead of at compile time.

Now you don’t even need to recompile to get all your protocols. You can define which protocol you want in your run-time configuration, or even command line arguments.

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Transferring control in simulations is a complicated dance. Both the relinquishing and the receiving simulations have to agree in principal and then exchange lots of complicated transactions to make the exchange. The complexity leaves most who attempt it frustrated and hopeless.

It doesn’t have to be that way. In VR-Link 5.1, MÄK offers you a technique to make the transfer of objects pre-approved and thus easy. Each participating simulation starts by agreeing to take any objects offered and agreeing to relinquish any objects asked for. With the approval steps out of the way, only a single message is needed to take control of another simulation’s airplane, for example. Similarly, with a single message your simulation can give back control when you are finished. We’ve included examples in VR-Link to illustrate this technique. So give it a try "” it’s actually kind of fun.

Background and Rationale

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MÄK has been a leader in interoperability for a long time. We have an industry-leading RTI, the MÄK RTI and  DIS/HLA interoperability library, VR-Link. MÄK is excited to add to our interoperability success with the new MÄK FOM Editor. The MAK FOM Editor is a free, web-based application where customers can build and manage their own FOMs (Federate Object Model).

(If you’re too excited to keep reading, you can get right to work by going here.)

For those of you who want to learn a bit more before you start typing, this is the first of several blogs that will discuss the tool and some of the rationale behind it.

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We’re not the only people using WebLVC. SILKAN, a French integrator of leading-edge, simulation-based solutions used worldwide for the design, optimization, testing, operation, and maintenance of complex systems, with assistance from Antycip Simulation, is reaping the benefits of web technology too. At Eurosatory 2014, an international land defense exhibition, SILKAN used the MÄK WebLVC Server to demonstrate the next-generation mobile instructor station for armored vehicle training systems. SILKAN’s prototype offers instructors a user-friendly and flexible way to control and monitor simulation sessions, thus opening new ways to leverage training.

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Programming languages have been evolving since the first computer was created. Early languages, including Autocode, FORTRAN, and FlowMatic, made way for many of today’s modern languages. The era of the C language introduced better structure and access to low-level system functions and devices. Then came C++, adding object-oriented programming constructs. Now we have a whole class of simple, modern, general-purpose, object-oriented programming languages, like C# (pronounced C sharp), that are gaining popularity.

VR-Link has been with you since the beginning and we plan to be with you to the end. So "“ drum roll please "“ we are excited to introduce C# support for VR-Link! Because our C# implementation of VR-Link is built as a Common Language Infrastructure (CLI) library, you can build your applications using C# or any other language that conforms to the CLI standard. There are currently 32 separate languages that are a part of the CLI standard, including Python, Ruby, and Visual Basic, as well as functional languages like F# and Lisp. (Functional languages provide an incredible amount of power when manipulating objects or groups of objects - read more about programming with F#.)

MÄK wants to make your life easier and we hope that by adding C# and other CLI-compliant languages, we have. If you have questions or requests, get in touch with us at info@mak.com (or leave us a comment below)!

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More than 20 years ago, VT MÄK stepped into the Modeling and Simulation community and introduced our flagship simulation networking software, VR-Link. Since then, MÄK has remained focused on both our dedication to interoperability and the needs of our customers. We’ve been active participants in the development of industry standards and protocols through the Simulation Interoperability Standards Organization (SISO) and have built our products to ensure our customers can use the protocol of their choice. This has consistently made VR-Link the top HLA-DIS networking toolkit on the market and VT MÄK the top choice for distributed simulation software.

Continuing the MÄK tradition of listening, learning, and evolving, we’ve recently added even more capabilities to meet the growing needs of VR-Link users. Here is some of what you’ll find in VR-Link 5.1:

  • New C# library of objects and interactions "“ While a lot of our customers use C++ to build DIS or HLA compliant applications, many new projects are started using C# "” a simple, modern, and object-oriented programming language. VR-Link now empowers customers to use a library of C# objects and interactions with our VR-Link protocol-independent API. (Learn how MÄK is keeping pace with modern programming languages like C#!)
  • Continued focus on performance "“ Performance is a top priority at MÄK. We’ve put a lot of effort in VR-Link to ensure our customers can take advantage of multithreaded publisher lists; this enables users to tick all publishers with a single call, allowing them to update as fast as possible.
  • Easier FOM extensions "“ Enjoy a simpler way to access FOM extensions. If you have a FOM where one or more new attributes have been added, you can now easily access the attribute without writing any new code at all.
  • API Improvements "“ We have significantly simplified our API for transferring ownership in HLA, as well as for configuring dead reckoners and smoothers. This will greatly speed up development for our VR-Link customers. 
  • Compliant with RPR FOM 2.0, Draft 20 "“ You can rely on VR-Link to remain up-to-date with major standards. VR-Link now supports the latest draft of the soon-to-be-finalized RPR FOM 2.0 standard, defining HLA classes, attributes, and parameters that are appropriate for real-time, platform-level simulations.

Stay tuned for more blog posts highlighting VR-Link newest capabilities!! And as always, reach out to us at info@mak.com (or leave a comment below) to get more info!

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SISO’s annual Simulation Interoperability Workshop (SIW) will soon be here and as always, a number of us MÄKers will be in attendance.  There is a lot going on this year but one of the most notable "” at least in my (admittedly biased) opinion "” is the meeting of the RPR FOM PDG. Earlier this year RPR FOM 2.0 was successfully balloted, though with a number of comments. A small group of us has been working to resolve those comments and at SIW we’ll be holding a full PDG meeting to vote on final decisions (feel free to join us). That means we may soon have an official RPR FOM 2.0 standard!

Some of you are probably thinking, "What’s the big deal? I’ve been using RPR 2 for years." It’s true, many of us have been. Despite never being officially standardized, draft 17 of the FOM has become a de facto standard, used throughout the world in many important federations. But draft 17 had a number of issues which the RPR drafting group has been trying to address over the last couple of years. Perhaps the most glaring problem was the lack of support for HLA 1516-2000 or 1516-2010 (HLA Evolved). While a number of versions have been produced by different groups over the years, there was no one official version. On top of that we have fixed bugs, inconsistencies, poor datatype naming, and confusing descriptions and documentation. We now even have a modularized version for HLA Evolved. I am happy to say that I believe this is the best version of the RPR FOM yet. I encourage you all to check out draft 20 of both the FOM and the accompanying GRIM (Guidance, Rationale, and Interoperability Modalities) document.

If you are going to be at SIW and would like a higher level overview of RPR FOM history, what we’ve been up to lately, and where we think the FOM is headed in the future, I also encourage you to attend the presentation of a paper I co-authored with Björn Möller of Pitch Technologies, Patrice Le Leydour of Thales, and René Verhage of CAE titled "RPR FOM 2.0: A Federation Object Model for Defense Simulations."

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Now that VR-Link for C# is released, we are excited to build new simulations on top of C#. I personally find C# to be fantastic to work with, so I can't wait. But even more interesting is that VR-Link is actually built as a CLI (Common Language Runtime) library.

The CLI is an intermediate language that can be used to build applications on any other language that conforms to the CLI standard. There are many. As of this writing, Wikipedia (http://en.wikipedia.org/wiki/List_of_CLI_languages) lists 32 separate languages that can interface with a CLI library. This includes scripting tools such as Python, PHP, and Ruby, purer languages such as Eiffel, and commonly used simpler languages, such as Visual Basic! Our customers are no longer bound by language limitations and will now be able to choose the language strictly based on which one is more useful for the job. You can even mix and match as you please.

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MÄK is continually increasing the quantity and quality of the content provided with our products. When you use MÄK products you get a world of content: terrain databases, simulation models, human characters, behaviors "“ all kinds of awesome content to make your virtual environments rich and effective for training and experimentation.

VR-Forces has hundreds of simulation models representing different vehicle types you can use to develop your urban, military, or maritime scenarios. DI-Guy 13 adds more than 100 new human appearances and with the DI-Guy variation system, you can randomly mix bodies, faces, and clothing to make virtually unlimited unique appearances - build huge crowds where you never see the same person twice! Our SpeedTree animated 3D vegetation and foliage gives your outdoor scene the look and feel of the real world. And layer all of this content on top of our many terrain databases, including Hawaii and a Middle Eastern Village:

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MÄK is making a huge investment in our premier visual suite, VR-Vantage. Last year we made tremendous strides by adding ocean and maritime visualization. The work continues full force as we continue to improve our visual environment. The next release of VR-Vantage, 2.0, is planned for later this year and has two major directions: performance improvements and visual quality enhancements.

We are committed to improving performance in VR-Vantage. Look forward to shader optimizations that take advantage of game-based rendering techniques, an improved physics engine to enhance the visual interaction between objects (like ships that rock on the dynamic ocean), optimized loading algorithms for large terrains, and improved internal organization and grouping of geometries to maximize capabilities of the GPU. If that all sounds like techno-jargon, it is! We’re focusing on the complicated stuff so you can focus on better-looking, better- performing scenes that run at 60 frames per second (fps), the gold standard of smooth visualization.

Visually, we are concentrating on several areas: a beautiful environment, lighting effects (both day and night), improved trees and vegetation, and high fidelity sensor/camera modeling. Both the ocean and the sky in VR-Vantage have been greatly improved. The ocean supports many new features, including helicopter rotor wash, significantly faster/better wakes (both up close and from the air), and underwater crepuscular rays ("God Rays"). The sky draws faster and can be rendered with high-resolution clouds. Complex surf patterns on shorelines can now be configured through shape files, allowing surf to roll onto beaches and inlets accurately.

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While MÄK is based in Massachusetts, we have some very good friends down in Texas. If you are in Texas, or if you’re just simulating it, you know that the stars at night need to shine really bright. VR-Vantage can help with that. VR-Vantage uses a real star map to calculate thousands of star positions for every day of every year. The stars are accurate, and if you look closely enough, you can pick out some of the planets as well.

When you are simulating at night, it’s necessary to make some of the stars brighter, or perhaps play with the luminosity of the moon. Here’s how you can do that: While some of the details of sky configuration can be found in the GUI, some of the more obscure and advanced settings can be found in the file vrvantage/data/Environment/Sky/SilverLining.config. If you look through this file, you will see lots of ways to configure the Sun, Moon, Clouds, Stars, and the Atmosphere.

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What’s the difference between a dull, old model and a bright shiny, new model?

Turns out, it’s just texture maps. Oh yeah, and the VR-Vantage rendering engine. With VR-Vantage 1.6 all you have to do to get bumpy, shiny, and shady effects in your models is add normal, specular, and occlusion maps. That might sound pretty complicated. But really these are all textures that you can create with tools like Crazybump, Blender, and Photoshop.

Crazybump will take your texture map and guess what shape it is and then use that shape to generate (bake) specular, normal, and occlusion maps. But it’s just guessing. If you have a high-polygon count 3D model, then you can use tools like Blender to bake specular, normal, and occlusion maps from that model. And in Photoshop, you can paint specular maps by highlighting the shiny spots of your original texture.

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Whether you’re simulating characters on a plane, emergency responders tending to a car accident, soldiers fighting for a foreign military, or a businessman walking down a busy Brooklyn street, DI-Guy gives you the content to create scenarios in whatever setting you need.

But if you’re like us, you might need to see it to believe it. So go on, take a peek at some of the new character content available with the just-released DI-Guy 13!

di-guy-character-content1_v2

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