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Frequently Asked QuestionsThis document lists frequently asked questions about the HVRC LOD Tool. This document was last updated: 8th March 2005. Questions1.0 General
2.0 Getting Started
3.0 Problem Solving
Answers1.1 What is HVRC LOD Tool?The HVRC LOD Tool is a piece of software designed that was designed to help us (the staff of Halden Virtual Reality Centre) to configure and generate levels of detail when dealing with very large CAD models that can been converted to ISO VRML97. it was important for us to be able to configure generation for individual models once, and then be able to regenerate LODs if those models were later modified. Because of this the tool can be executed either as a graphical tool or as a batch process. The specification was written after we got tired of pleading with developers of commercial polygon reduction software to add features that would assist us in LOD generation. Three students from the local university college took up the challenge and wrote the first version in 2002. Now, after a little polishing and bug fixing, we are making this tool available to everyone. 1.2 Who is HVRC LOD Tool intended for?Us, but maybe you too? 1.3 Why should I use HVRC LOD Tool?Because its useful if you have similar needs to us. ie. that you have lots of large models that want to reduce and that you also want to use as the basis of level of detail data for insertion into a virtual environment in order to improve performance. You may also find it useful if you just want to perform polygon reduction and model simplification on ISO VRML97 files using the reduction features of Trapezium Software's Chisel combined with a graphical visualiser, so that you can immediately see the results. 1.4 How can I use the HVRC LOD Tool to optimise my workflowIf you have a set of CAD files that can change then you can, if you are lucky(!), configure LODs once visually, save the configuration file, and then batch (re)generated LOD data later. You can also use thje HVRC LOD Tool to generate LOD data without intervention, however the success of this can vary from very good to mediocre. This is possible both in the interactive and batch run-time modes. The HVRC LOD Tool's configuration file format is XML-based so it is possible to write scripts that generate configuration files and the run threm through the LOD Tool in batch mode.
1.5 How much does HVRC LOD Tool cost?Its free! Note that you get what you pay for: No guaranteed support, limited documentation, and no guarantee that it will work or that it will not destroy you data, computer, or life. You may not redistribute it without permission or sell it. It is not open source. The licensing details are available on the HVRC LOD Tool product web pages at: http://www.ife.no/vr/products/lodtool/info/licensing.html If you find the HVRC LOD Tool, please tell your friends and send let us know that you like it. We like to receive encouragement as well as bug reports! 1.6 What 3D geometry formats does HVRC LOD Tool support?Uncompressed ISO VRML97. If you need to handle X3D or other file formats then you will need to use a file converter to prepare your data. 2.0 What are the minimum requirements for using HVRC LOD Tool?The minimum recommended requirements for the HVRC LOD Tool Tools is:
It will run on even older hardware, depending on what you consider usable performance... If you intend to use HVRC LOD Tool in you day-to-day work then we would recommend investing in a newer computer with more RAM and a faster graphics card than the one described as a minimum above. Note that the Direct3D version of Java 3D is not compatible with Windows NT 3.x or 4.x. Please use the OpenGL version of Java 3D if you are using Windows NT. The Direct3D version of Java 3D is available from Sun Microsystems (see web address provided above). 2.2 Will HVRC LOD Tool run on my computer and operating system?Probably. In theory, the HVRC LOD Tool runs on all operating systems that support the minimum Java requirements (Java 1.4.2 and Java 3D 1.3.1). Of course, the minimum hardware requirements, equivalent to those listed in the question above should be met. It was mostly developed on computers running Mac OS X 10.3.3, with some code developed under Windows 2000 and XP, and has been thoroughly tested on those platforms. It is also know to run under Linux (Mandrake). Platforms that it has not been tested under but under which it should run as-is include Sun Solaris and SGI IRIX. The Sun's Java 3D web page provides additional information about which platforms support Java 3D 1.3.1. In fact the minimum system permitted by HVRC LOD Tool is Java 1.3.1 and Java 3D 1.2.1, which allows it to be executed on a wider variety of platforms, however Java 1.4.2 and Java 3D 1.3.1 (in particular) fix a number of bugs so using the software with these earlier software versions is not recommended. Mac OS X Users: See "Does HVRC LOD Tool support Mac OS X?" below for additional information. 2.3 Does HVRC LOD Tool support Windows 98?HVRC LOD Tool is not recommended for, or tested under, Microsoft Windows 98, however it may work. See also the question "Will HVRC LOD Tool run on my operating system?". 2.4 Does HVRC LOD Tool support Linux?In theory, yes. In practice, it usually works fine, but some graphics cards have poor 3D support under Linux which may give unpredictable results on some systems. The installer includes Java 3D to simplify the installation process. See also the question "Will HVRC LOD Tool run on my operating system?". 2.5 Does HVRC LOD Tool support Mac OS X?The HVRC LOD Tool runs on Mac OS X 10.3 ("Panther") with the Java 3D 1.3.1 update installed. The Java 3D update is available via the operating system's Software Update mechanism or from Apple's website. However, our installers do not currently support Mac OS X. A separate Mac OS X package is provided for download. Under MacOS X, at least 512MB is recommended and a graphics card with at least 32MB RAM si preferable. The HVRC LOD Tool cannot be run on older machines running Mac OS 9 or earlier. Sorry. See also the question "Will HVRC LOD Tool run on my operating system?". 2.6 Which version of the installer should I use? "Includes" or "without" Java VM?If you already have Java 1.4.2 installed on your computer then you can use the "without Java VM" version. Otherwise you should use the "includes Java VM" version. If you are not sure (or don't really understand any of this) then use the "includes Java VM" version (if available for your platform). If you perform a default installation without changing any options in the installer then the "include Java VM" should install and set everything up correctly for you. If you use the "without Java VM" version of the installer to install on a system with Java 1.4.2 but without Java 3D installed, then you will need administrator privileges to install successfully as the installer will need to add Java 3D to your Java installation for you. 3.1 Where should I send bug reports?Please send bug reports to vr-support@hrp.no. If possible, please include a copy of the technical details from the HVRC LOD Tool About box (use the Save button in the About window to save the details to a text file) when sending bug reports, and explain the actions taken that led to the discovery of the bug. Please check the answers to questions in this FAQ first as the majority of problems reported are graphics card driver issues which we have no control over and can only recommend upgrading drivers to the latest versions or installing the DirectX version of Java 3D rather than the default OpenGL version. 3.2 HVRC LOD Tool runs too slowly on my computer. Is there anything I can do to improve performance?If the 3D view is running slowly on your computer, and it is not because the model is particularly detailed, then you could try one or more of the following:
On computers with older graphics cards (in particular those with less than 16MB RAM), the performance is likely to be poor if you run the HVRC LOD Tool window at full-screen size if you are using a screen resolution greater than 1024x768. The reason for this is that your graphics drivers will revert to software rendering (ie hardware acceleration will not be available) due to insufficient display memory resources. Software rendering is very demanding on the computer so not only the 3D speed but also the overall responsiveness of the computer will be affected. On some older graphics cards and even some modern graphics chipsets on laptop computers, with limited OpenGL support and/or memory, you may find that the DirectX version of Java 3D will give better performance. It can be downloaded from Sun's Java 3D web site. See the question and answer below for details. 3.3 My computer crashes every time I run HVRC LOD Tool!If the software regularly crashes or hangs then check if there are newer drivers available for your graphics card from the card vendor. Most crashes reported to us are caused by driver problems that are, unfortunately, beyond our control. On Windows, it is sometimes helpful to switch to the Direct3D version of Java3D if there are stability issues with your graphics card's OpenGL driver. Java 3D installers are available from Sun Microsystem's Java 3D web site. If, after installing the client software on Windows, the tools refuse to start, stating that the software is incorrectly installed then your graphics card may not be OpenGL compatible. In this case you should also try installing the Direct3D version of Java 3D. When installing Java 3D using an installer from Sun, you may need to inform the Java 3D installer of the location of the bundled Java executable (if you used the "include Java VM" installer and installed the bundled Java version. In that case it is located in the HVRC LOD Tool directory in your program files directory. Typically: C:\Program Files\HVRC LOD Tool\jre\bin If neither the OpenGL or DirectX versions of Java 3D work for you then your PC and/or graphics card are probably inadequate to run the HVRC LOD Tool efficiently. One other possibility that will normally work in most cases is to turn off hardware acceleration in the Windows Display Properties control panel. This will force Java 3D to use a software renderer. Although this could be rather slow, it is generally a stable solution. 3.4 The whole user interface is flickering!On computers with nVIDIA Quadro-based graphics cards, you may need to adjust the OpenGL configuration of your display to prevent flickering of 2D user interface elements when the 3D view is refreshed. For Windows 2000/XP, the following procedure can be used to reconfigure the display:
3.5 I have an ISO VRML97 model but it won't load in the Model Bank Tool!The model loading mechanism that we use is very strict and therefore rejects files with any errors. It may also reject some VRML features such as scripts and sensors. VRML files containing geometry generated using JavaScript scripts will certainly not work. If you are using 3D Studio Max, then make sure that you have a recent VRML exporter. Early exporters distributed with 3D Studio Mac are known to export files with a number of errors. Most models exported from 3D modelling packages will load fine but may not look as you expect. The most common reason for this is that the origin of the model is not where we expect it to be should be (ie within the boundaries of the geometry of the model), or the model has been exported with an incorrect scale (1 VRML unit is 1m). 3.6 The HVRC LOD Tool crashes while (or after) loading a large model!The most likely reason for this is that HVRC LOD Tool is running out of memory as the model is too large to fit in the default memory allocation set aside for the HVRC LOD Tool by the Jave run-time system. HVRC LOD Tool has been preconfigured to give a balance of performance and memory consumption that should work well for the majority of users, however if you attempt to load very (file size and/or number of polygons) large models then the HVRC LOD Tool may run out of memory. To allocate more memory to the HVRC LOD Tool tool under Windows or Linux/Unix:
Under Mac OS X, you need to right click (or control-click) on the application icon, select Show Package Contents, locate the info.plist and then look for the values described above and modify them. Note that allocating more memory may have a detrimental impact on the performance of the HVRC LOD Tool you do this for if your computer does not have enough real memory. The solution in that case is to add more physical RAM to the computer. Models that are so large that this problem occurs are typically too large to run efficiently on an average office PC. If you are running on a high-end workstation with a powerful graphics card then the memory configuration adjustment described above is an appropriate solution however if you are not then you should probably reduce the complexity of the model using a third-party polygon reduction tool before attempting to load it into HVRC LOD Tool. It will also be necessary to update the memory allocation each time you upgrade the HVRC LOD Tool as the lax files will be overwritten if the HVRC LOD Tool is reinstalled. On a machine with less than 256MB RAM, you may wish to reduce the default values in order to obtain better performance working with smaller models. |
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