Free Online EULUMDAT (LDT) Viewer (No Signup)
Also opens DWG, DXF, STEP, IGES, IFC, SKP, STL, OBJ, GLB, FBX, 3DM and other 3D/CAD files. Drop any file on the viewer.
Works directly in Chrome, Firefox, Safari, and Edge
Also from Innerscene: Circadian Lab, a free lighting calculator for room illuminance, melanopic EML, and glare.
What Is an EULUMDAT (LDT) File?
EULUMDAT is the photometric format European manufacturers publish and DIALux and Relux read. It is a plain list of values, one per line: the manufacturer, the luminaire type and symmetry, the luminaire and luminous-area dimensions in millimetres, one or more lamp sets (count, type, flux, colour temperature, colour rendering, watts), then the C-plane and gamma angles and the intensity table in candela per 1000 lumens.
This viewer scales that table to absolute candela, expands it from its symmetry (none, rotational, C0-C180, C90-C270 or quadrant) to a full 360 degrees and draws the photometric web: each direction at a distance proportional to its intensity, coloured from blue (dim) to white (peak). The C0-C180 and C90-C270 polar curves run through it, the luminaire body sits at the centre from the stated dimensions, and the status line gives the lumens, peak candela, beam and field angles, wattage, lamp, colour temperature and manufacturer. Open in IES Viewer takes the file on to the IES Viewer, which reads LDT too, for the polar plot and the isofootcandle plan.
Who Uses EULUMDAT (LDT) Files?
Lighting designers working with European manufacturers; DIALux and Relux users who want to look at a fixture’s distribution without opening a calculation project; architects, specifiers and wholesalers checking a datasheet’s numbers; and anyone sent an .ldt who has no lighting software installed.
Common Use Cases
- See a European luminaire’s beam shape in 3D without DIALux or Relux
- Read lumens, peak candela, beam angle, wattage and colour temperature from an .ldt
- Check which symmetry a file uses and how the C-planes differ
- Export the photometric web as GLB, OBJ, STL or USDZ for a render or AR
- Share the 3D web as a link or a self-contained HTML page
Features
3D Photometric Web
The intensity distribution drawn as a solid you can orbit, each direction at a distance proportional to its candela.
Absolute Candela
Intensities stored per 1000 lumens are scaled by the lamp flux, the way DIALux and Relux read them.
Every Symmetry
No symmetry, rotational, C0-C180, C90-C270 and quadrant files are all expanded to a full 360 degrees.
Polar Curves in 3D
The C0-C180 and C90-C270 curves drawn as lines through the web, the classic polar diagram in space.
Luminaire Body
A box or cylinder at the centre, from the luminaire length, width and height in the file.
Numbers on the Status Line
Lumens, peak candela, beam and field angle, watts and lm/W, lamp, colour temperature and manufacturer.
Open in the IES Viewer
One click hands the file to the IES Viewer for the polar plot, the isofootcandle plan and the zonal lumen table.
Export the Web
Save the photometric web as GLB, OBJ, STL, USDZ, a self-contained HTML page or an image.
Nothing Is Uploaded
The file is read entirely in your browser. No account, no upload, no copy on a server.
Share and Embed
Send a link that opens the 3D web in any browser, or drop the viewer into your own page with one iframe.
Compatibility & Format Notes
Reads EULUMDAT files with every symmetry indicator (Isym 0 to 4), equidistant and non-equidistant C-planes, several lamp sets (the first is used for scaling) and files marked as absolute photometry. The colour temperature is read whether it is given in kelvin, as a European colour code such as 830, or as text. EULUMDAT carries no magic header, so a file is recognised by its .ldt extension together with the shape of its first lines; a text file named .ldt that is not EULUMDAT opens as text. A file whose intensity table is missing or cut short gets a notice asking for a fresh copy. North American IES files open on the IES 3D viewer page.
Embed on Your Website
Add this viewer to your own site with a single line of HTML. Click Embed in the toolbar to generate an embed code, or use the snippet below with your own file URL.
Your Files Stay on Your Computer
Your EULUMDAT (LDT) files are parsed entirely in your browser. Nothing is uploaded, stored, or shared unless you explicitly click the Share button. Shared files are hosted for 90 days then deleted.
Frequently Asked Questions
▶How is an EULUMDAT file different from an IES file?
Both describe the same thing, a luminaire’s candela distribution. EULUMDAT stores intensities per 1000 lumens and adds standard fields for colour temperature, colour rendering and downward flux; IES stores absolute candela with free-form keyword lines. The viewer converts both to absolute candela and draws them the same way.
▶What does the 3D photometric web show?
Every direction the luminaire sends light, drawn at a distance proportional to the candela in that direction, coloured from blue for dim directions to white at the peak. The two coloured lines are the C0-C180 and C90-C270 polar curves.
▶Which lamp set does the viewer use?
The first one, which is the set the intensity table was measured with in almost every file. Its flux scales the table from candela per 1000 lumens to absolute candela, and its type, colour temperature and wattage go on the status line.
▶Can I get the polar diagram and an isofootcandle plan?
Yes. Click Open in IES Viewer on the status line. The file moves over already parsed, with the polar plot, the isofootcandle plan and the zonal lumen table.
▶Is this EULUMDAT viewer really free?
Yes, completely free. No signup, no watermarks, no file size limits on the viewer (the optional share-link feature has a 100 MB upload cap). Built by Innerscene as a tool for architects, engineers, and designers.
▶Are my files uploaded to a server?
No. All parsing, rendering, and conversion runs in your browser — nothing is uploaded, stored, or transmitted by default. The Share button is the only feature that uploads a file, and only when you explicitly click it.
▶Can I convert to another format?
Yes. The photometric web is a 3D mesh, so the Export menu offers GLB, OBJ, STL, PLY, USDZ, 3MF, VRML, STEP, DXF and 3DM, a self-contained HTML page, PDF and PNG or JPG images of the view. The viewer does not write .ldt files.
▶Can I embed this viewer on my own site?
Yes. Click Embed in the toolbar to generate a one-line <iframe> snippet you can paste into any HTML page. You can choose whether the embed shows the viewer’s toolbar.