IES Light Artifact

[rodbrew]

Hi,

We recently received a professionally created ies file for a vehicle headlight. Here is the header information.

IESNA91
[TEST] 010124-01
[TESTLAB] Optics & Photometrics Lab
[MANUFAC] Intertek, Grand Rapid - Photometric Lab
[LUMINAIRE] Lincoln N/A TBE Qu-00667947 Low Beam ESI
[LAMP] 12.8V / 5A
[ISSUEDATE] 1/14/2016 1:58:33 PM
TILT=NONE
1 550.566931 1.000000 21 121 3 1 0.000000 0.000000 0.000000
1.000000 1.000000 53.675013

-10.00 -9.00 -8.00 -7.00 -6.00 -5.00 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00

-60.00 -59.00 -58.00 -57.00 -56.00 -55.00 -54.00 -53.00 -52.00 -51.00 -50.00 -49.00 -48.00 -47.00 -46.00 -45.00 -44.00 -43.00
-42.00 -41.00 -40.00 -39.00 -38.00 -37.00 -36.00 -35.00 -34.00 -33.00 -32.00 -31.00 -30.00 -29.00 -28.00 -27.00 -26.00 -25.00
-24.00 -23.00 -22.00 -21.00 -20.00 -19.00 -18.00 -17.00 -16.00 -15.00 -14.00 -13.00 -12.00 -11.00 -10.00 -9.00 -8.00 -7.00 -6.00
-5.00 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00
18.00 19.00 20.00 21.00 22.00 23.00 24.00 25.00 26.00 27.00 28.00 29.00 30.00 31.00 32.00 33.00 34.00 35.00 36.00 37.00 38.00
39.00 40.00 41.00 42.00 43.00 44.00 45.00 46.00 47.00 48.00 49.00 50.00 51.00 52.00 53.00 54.00 55.00 56.00 57.00 58.00 59.00
60.00

The problem is that there is a very bright and chaotic artifact below the plane of the accurate light. I seem to recall that we had this problem before with an ies file that we created. I believe we were able to fix it by zeroing out the data down to -90 degrees and up to 90 degrees. I'm assuming the vrayies light might be expecting an ies file with a range with a multiple of 90 degrees in the horizontal. Is this the case? If so is this a standard of the ies file format? If not would it be possible to have the ies light modified to address this problem? Otherwise I could modify the file but since this came from a separate company I'd prefer not to for potential legal reasons.

This image shows the bright area below what I guess would be the -10 degree verticle line.


Let me know if you need further information or the full ies file.

Thanks,
Rod

[matanov]

Hi Rod,

With the pasted info above I get similar result when putting it in a VRayIES, but also I get a lot of errors when loading it in a 3ds max Photometric light. Can you send us the full ies ? (peter.matanov@chaosgroup.com)

[rodbrew]

Thanks Peter,

I just emailed you the file.

Rod

[vasil.minkov]

Hi Rod,

This is Type A IES file. For Type A photometry, the vertical angles should be in the range of [-90, 90] degrees or [0, 90 ] degrees.
The horizontal angles should be in the range of [0, 90] degrees for laterally symmetric luminaires and in the range of [-90, 90] degrees for luminaires that are not laterally symmetric.

You could add -90 and 90 degrees in order to comply to IES file requirements:

IESNA91
[TEST] 010124-01
[TESTLAB] Optics & Photometrics Lab
[MANUFAC] Intertek, Grand Rapid - Photometric Lab
[LUMINAIRE] Lincoln N/A TBE Qu-00667947 Low Beam ESI
[LAMP] 12.8V / 5A
[ISSUEDATE] 1/14/2016 1:58:33 PM
TILT=NONE
1 550.566931 1.000000 23 123 3 1 0.000000 0.000000 0.000000
1.000000 1.000000 53.675013

-90.00 -10.00 -9.00 -8.00 -7.00 -6.00 -5.00 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 90.00

-90.00 -60.00 -59.00 -58.00 -57.00 -56.00 -55.00 -54.00 -53.00 -52.00 -51.00 -50.00 -49.00 -48.00 -47.00 -46.00 -45.00 -44.00 -43.00
-42.00 -41.00 -40.00 -39.00 -38.00 -37.00 -36.00 -35.00 -34.00 -33.00 -32.00 -31.00 -30.00 -29.00 -28.00 -27.00 -26.00 -25.00
-24.00 -23.00 -22.00 -21.00 -20.00 -19.00 -18.00 -17.00 -16.00 -15.00 -14.00 -13.00 -12.00 -11.00 -10.00 -9.00 -8.00 -7.00 -6.00
-5.00 -4.00 -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00
18.00 19.00 20.00 21.00 22.00 23.00 24.00 25.00 26.00 27.00 28.00 29.00 30.00 31.00 32.00 33.00 34.00 35.00 36.00 37.00 38.00
39.00 40.00 41.00 42.00 43.00 44.00 45.00 46.00 47.00 48.00 49.00 50.00 51.00 52.00 53.00 54.00 55.00 56.00 57.00 58.00 59.00
60.00 90.00

You would also have to modify the measured values by adding leading row of 23 zeroes, trailing row of 23 zeroes and leading + trailing zero on the remaining rows of luminous data:
00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00
00.00 xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx 00.00
00.00 xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx 00.00
00.00 xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx xx.xx 00.00
......
00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00 00.00