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McIDAS-V Technical Issues

This document addresses key technical issues associated with memory use, Java3D graphics drivers, and remote display in McIDAS-V. It explains the default memory settings, the differences between 32-bit and 64-bit Java environments, and their implications on performance. The guide covers common errors, such as excessive CPU usage and graphics display problems, as well as solutions like updating graphics drivers. It also details background processing methods without GUI, utilizing Xvfb for virtual display capabilities.

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McIDAS-V Technical Issues

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  1. McIDAS-V Technical Issues • Memory use • Java3D / Graphics drivers • Remote display • Background processing

  2. McIDAS-V Memory Use • Data is normally represented as 32bits per data point (work is being done to represent ADDE imagery as 8bit) • Ancillary information is propagated with data objects • Units • Error estimates • Navigation • Java Virtual Machine controls memory garbage collection

  3. Java Memory Use • McIDAS-V will use 80% of available memory by default (heap size) • 32bit Java can address a maximum of 1536mb RAM • 64bit Java can address all available system RAM • Garbage collection is controlled by the Java Virtual Machine • Many factors affect garbage collection timing • Aggressive memory use is good for performance Total available (Heap size) Maximum Current

  4. Java3D / Graphics drivers • McIDAS-V uses cutting-edge 3D features • Java Runtime Environment version 5 and Java3D 1.5 are included as part of the installers • Many runtime errors can be fixed by updating your graphics card drivers • McIDAS-V fails to launch • Excessive CPU usage (100%) • “Torn” or gray images • Java3D error messages

  5. Setting the JRE on OS X • Core 2 Duo Macs running OS X 10.5 Leopard include Java 5 (32 and 64bit) and Java 6 (64bit) JREs • Apple does not provide Java 6 or Java 5 64bit for PowerPC or older Intel Macs • The “Java Preferences” utility is used to specify the current JRE

  6. Remote Display • “export DISPLAY” does not work with McIDAS-V • Java3D does not use the X11 window system • A local OpenGL graphics resource is required • Accelerated graphics card • 3D library (e.g., Mesa) • Java3D and OpenGL enable the powerful visualization capabilities of McIDAS-V

  7. Background Processing • Running McIDAS-V without creating a graphical user interface • Offscreen rendering with the “offscreen” option • Requires an active window manager • User must be logged in • Xvfb provides a virtual display resource for Java3D • Installed by default on newer Red Hat 5 systems • Freely available for most UNIX-like OSs • Binary packages • Source

  8. Running McIDAS-V using Xvfb • Create a virtual Xvfb display on screen :1.0 Xvfb :1 -screen 0 1024x768x24 & • Set your display for McIDAS-V to :1.0 export DISPLAY=:1.0 • Start McIDAS-V with a bundle or ISL file to process runMcV <bundle>

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