# Bump Scanner Unit (formerly Bump Map)

I have used bump maps in graphics and video, but I have never heard of this in a digital audio context. Is this an O|D original, as it pertains to the audio domain?

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Sweet Jeezus donâ€™t tempt me as Iâ€™m still over here tripping on other stuffâ€¦

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Wonâ€™t be able to try 0.3 for a little while yet but sounds like this could be a pretty flexible distortion unit when an audio rate signal is the input.

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This will become famous for the dirtiest distortion in modular: no joke.

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From what I see so far, @Joe it looks like we could use this for conditions instead of rational VCAâ€™s if running CV through it.

You can set:

Center, width, height and fade. It would output a signal based on the center position with a window the size of width. and yeah - oh man, running audio through this creates some absolute anger!!! Cool!

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Oh. Yeah!

When I read the description my head registered â€śparabolic wave shaperâ€ť with control over the parabolic equation. But sounds like this might be the windowing function we talked about in the sequential switch thread, eh?

i think think so! It looks that way when i tested it with a sin wave, you could pic the part of the waveform level you want as a threshold (i believe this is the center), and then the height from that threshold in both directions is the Width. So if you were feeding it some CV - if it hits an exact spot, itâ€™ll let it through the window and you can use that to make a trigger. Or, if audio, angry yuckiness!

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Bump Map was inspired by @Joeâ€™s sequential switch patch.

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as i understand it this is a comparatorâ€¦or sort of, it doesnâ€™t create a gate or trigger, it just letâ€™s a defined part of the incoming voltage through, right?

You could use 4 Bump Maps controlling the levels of 4 VCAs whose outputs are all summed together to create this:

http://www.doepfer.de/a144.htm

Here is the original picture from the thread where the Bump Map unit was first discussed:

The input value is on the X-axis and the resulting output is on the Y-axis. I like to think of them as â€śsoftâ€ť selections. You are â€śselectingâ€ť a portion of the range of a signal. If you change the fade to 0 then it would be a hard selection (output is high only in a certain interval of the input).

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hm, ok so center determines the voltage where you select a portion of, width the q setting of that portion but what does height do exactly?

In those terms, I guess you could think of height as equivalent to output gain (which can also be negative btw).

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ok, all clear now, very interesting unit i have to say

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Can you guys share some use cases for the bump map? I donâ€™t quite understand it yet.

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Essentially, you can use it as an n-channel crossfader. Examples include the A-144 MC above, the RxMx, or the Mixiplexer.

Right now, you could hack together a wavetable oscillator by using one Sample Player per waveform and using a bunch of these to crossfade between each player. You would set them up so that as they receive a shared voltage, only one Bump would be prominent at a time. The outputs of each Bump Map would control a VCA after each Sample Player, and the Sample Player outputs would feed a single mixer.

You could also hack together a quad panner using the same idea, but each VCA would have a separate channel output instead of being mixed together. You would also feed the four VCAs one shared input instead of four different inputs.

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Brilliant

Iâ€™m not sure I see the point of overloading a term from computer graphics to describe a unit that implements an established and well known mathematical function. Itâ€™s more obfuscating than illuminating, in my opinion.

Suggestions for names are always welcome. I just ask that you first test your idea using the Rename Unit function to see if it fits in the header.

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You got it. Iâ€™ll also try to eat a little breakfast before posting suggestions to cut down the curtness and pedantry.

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i build a video module that does this as a 40Mhz 4 input interpolating scanner. I just call it a video scanner

i loooove scanners and cronenberg

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