Twist warping question

[80sTherapy]

I'm trying to design a black hole and create a gravity warping effect similar to the one on the attached pictures. I'm using the twist warp effect but it doesn't quite objects closer to the edges of the canvas much. Is there a way to more strongly apply the twisting effect away from the center?

[carl123]

If you also have APhoto you have the twirl filter. Which may be useful.

https://affinity.help/photo2/English.lproj/index.html?page=pages/Filters/filter_twirl.html?title=Twirl

[Callum]

Hi 80sTherapy,

I believe your best bet would be to try the filter Carl123 mentioned above in Photo and then clean up any parts as necessary via the liquify persona.

Thanks
C

[GarryP]

14 hours ago, 80sTherapy said:

I'm trying to design a black hole and create a gravity warping effect similar to the one on the attached pictures.

Are you trying to show gravitational lensing, or heated stuff falling into a black hole, or both?

One of the problems with using a Twist (Warp or Filter) is that gravitational lensing doesn’t ‘twist’ the light.

The light from the stars and galaxies behind the black hole is being ‘bent’ around the black hole, from far away towards us, and ‘smeared’ across an area that we can see, the amount of ‘smear’ being dependant upon where the object is behind the black hole relative to us (in my very, very, limited understanding of what’s going on). 

Adding a ‘twist’ will make it look nice but it won’t make it look ‘realistic’, if that’s what you are going for.

The light from heated dust and other things that are falling into the black hole will emit light and that will often look somewhat ‘twisty’ as it spirals down to the event horizon but the gravitational lensing doesn’t ‘twist’ because the things that are emitting the light behind the black hole aren’t moving ‘around’ the black hole in a way for them to look ‘twisty’ (if you know what I mean).

Some kind of ‘fish eye’ effect might be more useful for making a gravitational lensing effect but I’m not sure how.

Note: I am not an astrophysicist.

[80sTherapy]

26 minutes ago, GarryP said:

Are you trying to show gravitational lensing, or heated stuff falling into a black hole, or both?

One of the problems with using a Twist (Warp or Filter) is that gravitational lensing doesn’t ‘twist’ the light.

The light from the stars and galaxies behind the black hole is being ‘bent’ around the black hole, from far away towards us, and ‘smeared’ across an area that we can see, the amount of ‘smear’ being dependant upon where the object is behind the black hole relative to us (in my very, very, limited understanding of what’s going on). 

Adding a ‘twist’ will make it look nice but it won’t make it look ‘realistic’, if that’s what you are going for.

The light from heated dust and other things that are falling into the black hole will emit light and that will often look somewhat ‘twisty’ as it spirals down to the event horizon but the gravitational lensing doesn’t ‘twist’ because the things that are emitting the light behind the black hole aren’t moving ‘around’ the black hole in a way for them to look ‘twisty’ (if you know what I mean).

Some kind of ‘fish eye’ effect might be more useful for making a gravitational lensing effect but I’m not sure how.

Note: I am not an astrophysicist.

I was looking to show gravitational lensing, but I decided to simplify the design and swap the idea. Still interesting to work on, though. I did play with the fish eye effect. 

[markw]

@80sTherapy Just seen this thread and couldn’t resist having a play with the idea!
In the attached APhoto file, much simple fun is to be had sliding the Black Hole Group around! (I’m easily entertained!)
I’ve also thrown in two 4 Point star refractions, one Pixel the other Vector that I made for someone else around here🤔 some time back.

Black Hole.afphoto

[80sTherapy]

1 hour ago, markw said:

@80sTherapy Just seen this thread and couldn’t resist having a play with the idea!
In the attached APhoto file, much simple fun is to be had sliding the Black Hole Group around! (I’m easily entertained!)
I’ve also thrown in two 4 Point star refractions, one Pixel the other Vector that I made for someone else around here🤔 some time back.

Black Hole.afphoto

Wow! That looks fantastic. No idea how you achieved that, but I'll take a look at the file and see what I can learn. Thanks! 

[markw]

You’re welcome! I think the construction of the Black Hole is fairly self explanatory but if you do have questions, just ask away.

[80sTherapy]

On 12/2/2023 at 2:14 PM, markw said:

You’re welcome! I think the construction of the Black Hole is fairly self explanatory but if you do have questions, just ask away.

I have a couple, actually. Very succinctly, how did you manage to create the dynamic warping? I didn't even know AP could do that. Also, how would you go about creating an accretion disk - including the light gravitational warping - similar to the one in the attached pic? I'm thinking pen tool to create the various rings > expand stroke > color and fx as needed (glow, gaussian blur...). Not sure if there's a quicker/easier way to go about this and would love your insight. 

Cheers! 

P.S. Is it OK for me to reuse that star?

 

[markw]

The Live filters in Affinity are just that “Live” so one interesting side effect is that if you put the Warp Pinch/Punch filter inside a Group it becomes possible to move it around the canvas, with the layers underneath it affected in real time.
Also one filter on it’s own isn’t strong enough to bend the stars sufficiently, but when stacked each filter is amplifying the effect of the ones below it.
I’m not sure about the accretion disk thing? Was there supposed to be another example image of what you are aiming for with that attached to your last post?

As for the two stars, yes of course reuse them as much as you want in other things!

[loukash]

On 11/29/2023 at 4:19 PM, GarryP said:

Adding a ‘twist’ will make it look nice but it won’t make it look ‘realistic’

A kind of a twist effect can be realistic e.g. when the black hole pulls matter from a nearby star which would then rotate around the "hole".
Here interesting reading with the actual photo of a real black hole:
https://new.nsf.gov/news/astronomers-capture-first-image-black-hole

An Intervebz search will reveal many more or less scientifically plausible visualizations as well:
duckduckgo.com/?q=black+hole

Hm… I think I'd utilize the brand new Spiral tool here, whaddyathink…? 

[80sTherapy]

2 hours ago, markw said:

The Live filters in Affinity are just that “Live” so one interesting side effect is that if you put the Warp Pinch/Punch filter inside a Group it becomes possible to move it around the canvas, with the layers underneath it affected in real time.
Also one filter on it’s own isn’t strong enough to bend the stars sufficiently, but when stacked each filter is amplifying the effect of the ones below it.
I’m not sure about the accretion disk thing? Was there supposed to be another example image of what you are aiming for with that attached to your last post?

As for the two stars, yes of course reuse them as much as you want in other things!

Thanks! Oops, yes, I meant to attach this picture:

[NotMyFault]

There are 3 areas in your example:

1. the base image of a ring
2. the foreground area. This can be created by perspective distortion filter, masked to the lower half of the ring
3. the transition area, roughly a segment of the circle from 1 to 2 and 10 to 11 o’clock.

1 and 2 can be easily created.

3 is much harder. It would require perspective filter strength linearly adjusted between 0 and 100%. Not on the opacity scale, but on the node position of the filter handles. Unfortunately this is not possible in Photo.

Alternatively, it might be possible with a very complex equations filter. Unfortunately equations is destructive only, and does not allow to save / restore equations to tweak them easily. 

The next candidate is polar to rectangular (or invers).

The last resort options are using fiel blur or liquify. 

 

[GarryP]

6 hours ago, loukash said:

A kind of a twist effect can be realistic e.g. when the black hole pulls matter from a nearby star which would then rotate around the "hole".

 

On 11/29/2023 at 3:19 PM, GarryP said:

The light from heated dust and other things that are falling into the black hole will emit light and that will often look somewhat ‘twisty’ as it spirals down to the event horizon

 

[80sTherapy]

6 hours ago, NotMyFault said:

There are 3 areas in your example:

1. the base image of a ring
2. the foreground area. This can be created by perspective distortion filter, masked to the lower half of the ring
3. the transition area, roughly a segment of the circle from 1 to 2 and 10 to 11 o’clock.

1 and 2 can be easily created.

3 is much harder. It would require perspective filter strength linearly adjusted between 0 and 100%. Not on the opacity scale, but on the node position of the filter handles. Unfortunately this is not possible in Photo.

Alternatively, it might be possible with a very complex equations filter. Unfortunately equations is destructive only, and does not allow to save / restore equations to tweak them easily. 

The next candidate is polar to rectangular (or invers).

The last resort options are using fiel blur or liquify. 

 

Thanks for the input. I'm actually looking to do this in Designer. Photo came up because Designer apparently can't very effectively do the gravitational lensing effect.

Note that I'm not working on recreate an exact black hole. I'm working on a black hole themed version of a macOS app icon (both attached). The black hole and photon ring part are done (the photon ring might need to be tweaked - any feedback is welcome) but the developer wants to explore adding an accretion disk. I'm thinking using the circle tool angled like you showed, convert to curves and then use the node tool to shape the ring in the 10-2 o'clock area, plus the bottom part with separate half circles shaped as needed.   

[markw]

17 hours ago, 80sTherapy said:

Also, how would you go about creating an accretion disk - including the light gravitational warping - similar to the one in the attached pic? I'm thinking pen tool to create the various rings > expand stroke > color and fx as needed (glow, gaussian blur...)

Yes, in principle using the Pen tool + FX should work well in reproducing the various disc elements.
Another possible “quick and dirty” method though might be to vectorise a pixel image and edit that, if scalability is important.
I give you v2…
Black Hole.afphoto

[markw]

OK, not sure my last post will work for you🤫 as it seems you are actually wanting something for an App icon, which will probably need to be more stylised to fit what you have already icon wise…

[80sTherapy]

2 hours ago, markw said:

OK, not sure my last post will work for you🤫 as it seems you are actually wanting something for an App icon, which will probably need to be more stylised to fit what you have already icon wise…

I will try to create the disk from scratch. Good learning exercise! Thanks for all the help!