[Arcanjo7Sagi]

Originally Posted by Bramble Thorn

I would think if you had both extensions and could see the entirety of the electromagnetic spectrum, you would have effective darkvision all the time, barring extreme circumstances.

I saw a science show where they lit up the sky with all the cosmic rays we cannot see, and there was no black in the sky. And many of those rays can pass through matter so you can see them indoors.

Dark Vision and Hyperspectral Vision have different benefits. Both allow you to see in the dark, but in different ways. As far I know, in a total darkness, someone with Dark Vision would see better.

HSV, B60:

Hyperspectral Vision grants nearperfect night vision: you suffer no vision or combat penalties if there is any light at all. In total darkness, it functions exactly like Infravision.

And Infravision, also B60:

This lets you fight at no penalty even in absolute darkness, if your target emits heat (this includes all living beings and most machines). It also gives you +2 on all Vision rolls to spot such targets, since their heat stands out from the background.

(...)

Infravision does not let you distinguish colors, and only allows you to judge the general size and shape of heat-emitting objects, including living beings (for instance, you might have trouble telling two people of the same size apart). Roll at -4 to distinguish objects of similar size and shape.

Whyle, Dark Vision, in B47:

You can see in absolute darkness using some means other than light, radar, or sonar. You suffer no skill penalties for darkness, no matter what its origin. However, you cannot see colors in the dark.

Again, both allow you to see in total darkness. And you can not distinguish colors on either, not without a enhancements. But the benefits of each is distinct.

My point is: It doesn't seems to be cost-effective to have both. Since you already see in the dark somehow, the benefit of adding another full-cost advantage seems little. That's why I was thinking in merging both advantages somehow.