difference in end result between IES file and IES converted to LDT by Dialux program

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deech123
Posts: 26
Joined: Mon Jun 10, 2013 12:31 pm

difference in end result between IES file and IES converted to LDT by Dialux program

Post by deech123 » Wed Jan 09, 2019 1:06 pm

Hi guys,

after 1 day of investigation, and trying to test all possibilities we found a problem in de LDT editor of Dialux.
I will try to explain it in simple words.

we have our own .IES File we got back from light lab.
we make a building in dialux, and place this IES file for example 7x6 fixtures.

then we take the same .IES file and we open the LDT editor of Dialux.
we convert it to .LDT, and then open the project we allready have.
we change the fixtures one on one by the LDT file, what should be same.

well it's not.
we found out that if you do an UGR calculation the value of UGR is quit higher with the .LDT file comparing to the .IES file.

in our test projects we spend over 1 day to find the problem and we found it in the conversion, but don't ask me what is going wrong.
with our .IES file we got an UGR of 21.6, with the exact same building , just replacing the fixtures by the .LDT, we end up at 24.9, so this is 3.3 UGR higher than the IES files, for exact the same fixture and setup in the same buidling.

so this is hugh, since if you work on project where UGR is important then this can be a killer !
I do not know if you guys from Dialux have any knowledge on this, but I can always send you our files, and you will see the difference between .IES and converted .LDT.

so we know for the moment we must work with the .IES files and not longer with the converted .LDT.

and we know the IES file contains no height of fixture, but when you import into dialux evo latest version, you can enter these, so at this point, they are the same in length, height,etc..

greetz
Didier
Last edited by deech123 on Wed Jan 09, 2019 1:46 pm, edited 1 time in total.

Csuleiman
Posts: 1411
Joined: Wed Mar 07, 2012 3:07 pm

Re: difference in end result between IES file and IES converted to LDT by Dialux program

Post by Csuleiman » Wed Jan 09, 2019 1:18 pm

Hello Didier,

It would be of help if you could provide us with the IES and LDT files and also with both evo project files. We will try to analyse the problem as soon as possible.

Best regards,
DIAL Support Team

deech123
Posts: 26
Joined: Mon Jun 10, 2013 12:31 pm

Re: difference in end result between IES file and IES converted to LDT by Dialux program

Post by deech123 » Wed Jan 09, 2019 3:52 pm

HI,

just send an mail to support@dial.de, with the 2 dialux files,complete the same only the fixture is one time the IES an the other time the converted IES to LDT.
also you have the original IES file and the converted LDT also.

let me know what you found :-)

Didier

Csuleiman
Posts: 1411
Joined: Wed Mar 07, 2012 3:07 pm

Re: difference in end result between IES file and IES converted to LDT by Dialux program

Post by Csuleiman » Thu Jan 10, 2019 9:47 am

Hello Didier,

Thank you very much for sending us the projects and luminaire files.

We've checked your two luminaire files and determined that there are some differences. The length and width of the luminous area is different and so is the number of lamps. This is the reason why you don't get the same UGR value in your project files.

We just reviewed the original IES file in our LDT editor and saved the file as an LDT file again. Then we compared the photometric data of both files. The result is identical in both files. We would like to recommend you to check the LDT file which we have sent you via email in your project files again. Now the UGR value should be the same.

Maybe you can download and install once again our LDT editor to be able to save your IES files into the LDT file format.
https://www.dial.de/en/dialux/ldt-editor/

Best regards,
DIAL Support Team

deech123
Posts: 26
Joined: Mon Jun 10, 2013 12:31 pm

Re: difference in end result between IES file and IES converted to LDT by Dialux program

Post by deech123 » Fri Jan 11, 2019 7:40 am

hi,

yes I also got your email.
and indeed there was a very small difference in the light width settings in LDT that caused the big UGR difference.

thx for the quick action !
this topic can be closed.

thx
Didier

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