Light profile (IES)

General Discussion
1

Hello,

Looking at the UE4 engine document. I notice that the engine use IES Light Profile files to set the behavior of different lights and allow them to get closer to reality.

Thus the rendering of the lighting is more realistic since the deformations of the bulbs are taken into account as well as the different effects of lenses or even the shape of the bulb.

Lamp configurations can be downloaded to specialized sites that provide files with information

What do you think of this system ?
is it adaptable to JME ?
What would be the workload ?

Thoced

2

I guess it can be doable… is there a spec on how this data should be interpreted somewhere?

3

Looking at the IES file on the website:

I’m not sure but that’s what I understand by looking at the IES file specific to different fixtures.
I notice the following elements:

In the file, two first data vectors contain the different illumination ranges in degrees. (on a maximum of 180 °)
180 ° max for one axis and 180 ° max for a second axis.

Then values ​​are indicated in other vectors (intensity values?)

  • Value in a two-dimensional array, here the lamp illuminates on 180 ° in one axis and 90 ° in another axis:

candela

In the file ies:

Vector Axe 01 (Range 0 - 90 °):
0  2.5  5  7.5  10  12.5  15  17.5  20  22.5  25  27.5  30
32.5  35  37.5  40  42.5  45  47.5  50  52.5  55  57.5  60
62.5  65  67.5  70  72.5  75  77.5  80  82.5  85  87.5  90

Vector Axe 02 (range 0 - 180 °):
0  2.5  5  7.5  10  12.5  15  17.5  20  22.5  25  27.5  30
32.5  35  37.5  40  42.5  45  47.5  50  52.5  55  57.5  60
62.5  65  67.5  70  72.5  75  77.5  80  82.5  85  87.5  90
92.5  95  97.5  100  102.5  105  107.5  110  112.5  115
117.5  120  122.5  125  127.5  130  132.5  135  137.5  140
142.5  145  147.5  150  152.5  155  157.5  160  162.5  165  167.5  170  172.5  175  177.5  180

Then many vectors with intensity:

 1172  1207  1230  1177  1060  986  936  889  884  822  839
 800  754  705  670  668  652  659  675  718  708  709  739
 788  835  819  799  733  704  659  499  268  126  53  21
 2  0

 1172  1227  1236  1175  1055  992  935  898  885  833  848
 808  765  716  685  670  663  680  699  725  728  736  781
 834  889  885  864  764  720  637  463  239  109  47  17
 8  0

 1172  1220  1232  1172  1054  984  931  896  889  830  844
 804  771  733  687  671  672  700  737  740  739  770  819
 912  988  1004  959  855  724  591  455  217  102  42  14
 7  0
 
 1172  1233  1246  1187  1073  995  946  908  906  851  864
 823  805  764  699  681  691  738  779  793  793  845  916
1023  1160  1174  1032  885  640  517  385  180  85  40
16  4  0
 
 1172  1228  1241  1182  1073  995  950  911  913  858  884
 852  840  788  704  680  700  763  789  838  892  944  1022
 1176  1285  1224  1081  810  524  408  311  156  73  37
 18  8  0,,,,,,,, etc

So I think the values ​​in the table should be interpreted as a light intensity

4

Short google:
IES Standard File Format | 3ds Max | Autodesk Knowledge Network and iesna.org