Grenzwert
Medical Viewer
Last verified:
What is Grenzwert?
Grenzwert is a free, browser-based 3D DICOM viewer designed for viewing CT and MRI volumetric medical imaging data. It renders actual volumetric CT data with photorealistic, ground-truth path tracing directly in your web browser, delivering fidelity comparable to professional medical imaging workstations without requiring any software installation.
Key features include a real-time transfer function editor that lets you adjust opacity and color mappings to peel back layers of tissue, 3D ROI cropping to slice away unwanted volume sections, Window/Level control for contrast adjustment, and progressive streaming that loads coarse mip levels first then refines detail as you interact. The tool uses WebGPU for GPU-accelerated rendering with WebAssembly, supporting HDR pipeline features like bloom, auto-exposure, and ACES tone mapping.
Grenzwert is ideal for radiologists, medical professionals, medical imaging researchers, graphics engineers, medical students, and anyone needing to view DICOM CT/MRI volumes without installing dedicated software. It's particularly valuable for education, research, clinical demonstrations, and showcasing advanced volumetric rendering capabilities.
The viewer supports delta tracking with the Woodcock null-collision algorithm for unbiased volume rendering, Cook-Torrance GGX BRDF with Henyey-Greenstein phase function for physically accurate light scattering, and async mip-level streaming with gzip decompression for responsive interaction even with large volumetric datasets.
All processing happens locally in your browser using your machine's CPU, GPU, and disk resources—your medical imaging data never leaves your device or gets sent over the internet, ensuring privacy and HIPAA compliance for clinical use.
Grenzwert pricing
Pricing model: Freemium
Completely free with no paid tiers or subscription plans. The tool is offered as a free browser-based demo with all features available at no cost. Author Mikhail Gorobets provides the full source code on GitHub for free use and modification.
Grenzwert pros
- Completely free with no paid plans or subscription requirements
- No software installation needed—runs entirely in web browser
- Ground-truth path tracing delivers photorealistic medical imaging quality
- WebGPU acceleration provides professional-grade rendering performance
- Real-time transfer function editor for adjusting tissue opacity and color
- 3D ROI cropping lets you slice away unwanted volume sections interactively
- Progressive mip-level streaming ensures responsive interaction while loading
- HDR pipeline with bloom, auto-exposure, and ACES tone mapping
- Delta tracking using Woodcock null-collision algorithm for unbiased rendering
- Cook-Torrance GGX BRDF physically accurate light scattering
- All data stays locally on your machine—never uploaded to servers
- HIPAA-compliant since no medical data leaves your browser
- Supports both CT and MRI volumetric DICOM data
- Cross-platform C++ engine compiled to WebAssembly works on any modern browser
- Open source with full source code available on GitHub
- Async gzip decompression for efficient network streaming
- Multi-monitor and HiDPI support for professional workflows
- GPU tile culling and empty-space skipping for performance optimization
- No plugins or downloads required beyond modern web browser
- Interactive rendering responds instantly while adjusting parameters
Grenzwert cons
- Requires WebGPU support—only works in modern browsers with WebGPU enabled
- GPU-intensive rendering may struggle on older or low-end graphics cards
- Large volumetric datasets may take time to load despite progressive streaming
- Primarily optimized for CT data, MRI support may be less comprehensive
- No built-in PACS integration for hospital radiology workflows
- LacksDICOM SEG and RTSTRUCT support found in enterprise viewers
- No annotation tools like polygon contours or draggable text labels
- Missing standard 2D MPR cross-view synchronization some radiologists expect
- No built-in measurement tools for Hounsfield Units or calibrated distances
- No billing, appointment management, or patient records features
Frequently asked questions about Grenzwert
What is Grenzwert and what does it do?
Grenzwert is a free browser-based 3D DICOM viewer that renders volumetric CT and MRI medical imaging data with ground-truth path tracing directly in your web browser. It delivers photorealistic rendering quality comparable to professional medical imaging workstations, allowing you to view actual volumetric CT datasets with physically accurate light scattering through bone and soft tissue.
Do I need to install any software to use Grenzwert?
No installation is required. Grenzwert runs 100% in your web browser using WebGPU for GPU acceleration and WebAssembly for the rendering engine. It appears as a website but actually runs entirely on your machine using your CPU, GPU, and disk resources. No plugins or downloads are needed beyond a modern browser with WebGPU support.
Is my medical imaging data safe when using Grenzwert?
Yes, your data stays completely on your machine. When you load DICOM data into Grenzwert, it is loaded into your web browser and never sent out on the web. All processing happens locally using your machine's resources, making it HIPAA-compliant for clinical use since no medical data leaves your device.
What types of medical imaging data does Grenzwert support?
Grenzwert primarily supports CT (computed tomography) and MRI (magnetic resonance imaging) volumetric DICOM data. It is optimized for volumetric CT datasets and can load DICOM format files containing 3D volume data for rendering.
How does the transfer function editor work?
The transfer function editor lets you adjust opacity and color mappings in real time to peel back layers of tissue. As you modify the transfer function parameters, the renderer keeps up with interactive performance, allowing you to highlight specific tissue types or structures by adjusting how they appear in the volumetric rendering.
What makes Grenzwert's rendering different from other DICOM viewers?
Grenzwert uses ground-truth path tracing with delta tracking (Woodcock null-collision algorithm) and Cook-Torrance GGX BRDF with Henyey-Greenstein phase function for physically accurate light scattering. This delivers photorealistic, unbiased volumetric rendering that resembles professional medical imaging workstations, unlike simplified mesh approximations or stylized rendering in other viewers.
Does Grenzwert work on all computers and browsers?
Grenzwert requires a modern web browser with WebGPU support. The cross-platform C++ engine is compiled to WebAssembly, so it works on any platform with a WebGPU-enabled browser (laptop, tablet, or desktop). Rendering performance depends on your GPU—powerful GPUs provide fast, smooth renderings while older or integrated graphics may struggle with the computationally intensive path tracing.
How does progressive streaming improve the user experience?
Progressive streaming loads a coarse mip level first so you can start interacting immediately, then finer detail loads in as you idle. This means you're never waiting on a blank screen—Grenzwert responds instantly to your interactions and then sharpens the image as more data streams in with async mip-level streaming and gzip decompression.
Is Grenzwert open source?
Yes, the full source code is available on GitHub. You can examine the shader structure, understand how the streaming pipeline works, and modify the code. Author Mikhail Gorobets, a graphics engineer specializing in medical visualization and real-time rendering, has made the source publicly available.
What advanced rendering techniques does Grenzwert use?
Grenzwert employs several advanced techniques: MacroGrid acceleration with DDA empty-space skipping and GPU tile culling for performance, progressive frame accumulation that starts noisy and converges to ground truth, HDR pipeline with bloom and auto-exposure, ACES tone mapping, and async mip-level streaming with gzip decompression for efficient network usage.