How to warp a video mapping

JJHP3

Hi All - I have done lots of mapping in my time, but now I'm stuck. I'm projecting a thin vertical video of water/waves onto a 600 cm diameter vertical column using a short throw projector. Using IzzyMap of course... I want the waves more or less "level" across the column and the top and bottom of the thin video rounded to appear to wrap the column. I have used composite on the input for the rounded without luck and tried the grid setting for leveling. I have used just a few grid points thinking moving one might warp the rest of the points, but that didn't seem to work. I tried using 25 points on the long, vertical side and 4 on the horizontal and that didn't seem to work well at all. The bezier handles are so small and white, while my video is very light too. I made a dark grid image to test but I can't get that to warp the way I want it to.

Is there a way of using the grid to warp a column? For what it's worth, I have watched the guru session on mapping several times and read all there is on the Troika website on mapping too. Sorry to be dense and looking forward to any suggestions! - John

Woland

@jjhp3

Ideas:

Try using 3D
- Get a .3ds file of a column/cylinder (You should be able to use this .3ds file (though you'll need to modify it to make it taller either using the 3D Player or, failing that, Cheetah3D)
- Import the .3ds file into Isadora
- Drag it into the Scene Editor from the Media View to create a 3D Player actor
- Connect a Movie Player with your video content to the 'texture map' input of the 3D Player actor so it wraps your video around the 3d object
- Adjust the 3D Player actor and/or a 3D Stage Orientation actor until the content achieves the look you want on the column.

Try having an LLM write GLSL shader code to create a "cylinder warp" effect. (If you do this, feed it the section named "Tutorial 6: Adding GLSL Shaders to the Toolbox" from this article first and the example GLSL shader codes below so that it understands how GLSL shader code works in Isadora.)

Example Code 1:

/*
TT Bulge Distortion - Fragment Shader
version v1.0
Created for Isadora by Mark Coniglio
Based on Code in GPUImage by Brad Larsen 
https://github.com/BradLarson/GPUImage
*/
// ISADORA_PLUGIN_NAME("TT Pinch Distortion")
// ISADORA_PLUGIN_DESC("Creates a 'pinch' effect centered at the point specified specified by the 'horz center' and 'vert center' inputs. You can adjust size and intensity of the pinch using the 'radius' and intensity' inputs.")
// ISADORA_FLOAT_PARAM(radius, radi, 0, 200, 100, "Radius of the pinch effect.");
uniform float radius;
// ISADORA_FLOAT_PARAM(intensity, intn, -1000.0, 1000.0, 100, "Intensity of the pinch effect.");
uniform float intensity;
// ISADORA_FLOAT_PARAM(horz_center, ctrx, -100.0, 100.0, 0, "Horizontal center of the pinch effect.");
uniform float horz_center;
// ISADORA_FLOAT_PARAM(vert_center, ctry, -100.0, 100.0, 0, "Vertical center of the pinch effect.");
uniform float vert_center;
uniform vec2 resolution;
uniform sampler2D tex0;
void main()
{
    float aspect = resolution.x / resolution.y;
    vec2 uv = gl_TexCoord[0].xy;
// normalize
uv -= vec2(0.5);
// account for aspect ratio
uv.x *= aspect;
vec2 center = vec2(horz_center / 100.0, vert_center / 100.0);
vec2 dir = normalize( center - uv );
float d = length( center - uv );
float factor = 0.5 * intensity/100.0;
float f = exp( factor * ( d - radius/200.0 ) ) - 1.0;
if (d &gt; radius/200.0 ) f = 0.0;
 vec2 halfPixel = vec2(0.5, 0.5) / resolution.xy;
// account for aspect ratio
uv.x /= aspect;
// de-normalize
uv += vec2(0.5);
uv.x = clamp(uv.x, 0.0 + halfPixel.x, 1.0 - halfPixel.x);
uv.y = clamp(uv.y, 0.0 + halfPixel.y, 1.0 - halfPixel.y);
gl_FragColor = texture2D(tex0, uv + f * dir );

}

Example Code 2:



/*

TT Bulge Distortion - Fragment Shader

version v1.0

Created for Isadora by Mark Coniglio

Based on Code in GPUImage by Brad Larsen

https://github.com/BradLarson/GPUImage

*/

// ISADORA_PLUGIN_NAME("TT Pinch Distortion")

// ISADORA_PLUGIN_DESC("Creates a 'pinch' effect centered at the point specified specified by the 'horz center' and 'vert center' inputs. You can adjust size and intensity of the pinch using the 'radius' and intensity' inputs.")

// ISADORA_FLOAT_PARAM(radius, radi, 0, 200, 100, "Radius of the pinch effect.");

uniform float radius;

// ISADORA_FLOAT_PARAM(intensity, intn, -1000.0, 1000.0, 100, "Intensity of the pinch effect.");

uniform float intensity;

// ISADORA_FLOAT_PARAM(horz_center, ctrx, -100.0, 100.0, 0, "Horizontal center of the pinch effect.");

uniform float horz_center;

// ISADORA_FLOAT_PARAM(vert_center, ctry, -100.0, 100.0, 0, "Vertical center of the pinch effect.");

uniform float vert_center;

uniform vec2 resolution;

uniform sampler2D tex0;

void main()

{

float aspect = resolution.x / resolution.y;

vec2 uv = gl_TexCoord[0].xy;
// normalize
uv -= vec2(0.5);
// account for aspect ratio
uv.x *= aspect;
vec2 center = vec2(horz_center / 100.0, vert_center / 100.0);
vec2 dir = normalize( center - uv );
float d = length( center - uv );
float factor = 0.5 * intensity/100.0;
float f = exp( factor * ( d - radius/200.0 ) ) - 1.0;
if (d &gt; radius/200.0 ) f = 0.0;
 vec2 halfPixel = vec2(0.5, 0.5) / resolution.xy;
// account for aspect ratio
uv.x /= aspect;
// de-normalize
uv += vec2(0.5);
uv.x = clamp(uv.x, 0.0 + halfPixel.x, 1.0 - halfPixel.x);
uv.y = clamp(uv.y, 0.0 + halfPixel.y, 1.0 - halfPixel.y);
gl_FragColor = texture2D(tex0, uv + f * dir );

}

JJHP3

Wow - thanks you! I will attempt... what a wonderful group of people work with Isadora!

DusX

@jjhp3

Another option worth looking at is chaining together IzzyMap mappings. I find this adds more flexibility.
I often use one projector to mask and place my mapping content. This projector is sending to a virtual stage.
Then I use Get Stage Image to grab that IzzyMap work, and feed it into a second Projector where I use IzzyMap to Grid Warp as required.
I find this 2 phase approach to be much less confusing and easier to update over time.

JJHP3

@dusx Well I sure hadn't thought of that approach! I'll give it a try - thanks

JJHP3

@dusx And a secondary question about grid mapping... not sure how to ask, but if one has a 6 x 6 square grid, is there any way to grab and move one of the corners and all the other grid lines will warp proportionally? Or is grid a point by point process?

dbini

@jjhp3

as far as I know, grid mapping is done on individual points, but it would be really useful if other points could react - it would be a bit like the 'smudge' tool in photoshop.

jfg

@jjhp3

Yes and no. If you select multiple points (using the Shift key) and hold and drag a line between the selected points, all the selected points will move together. No, you can’t change the curve for several points. You can only do this for each point individually. Unless I didn't find how.

Best regards,

Jean-François

jfg

@jjhp3

Attached is a column made with Izzy Map and the Global Edge Blend Mask to make a shadow. Works if you don't need another background as black

you can also use the Edge Blend Mask actor instead of the global one.

I join a 3ds column if you prefer to use a 3d projector. You don't need the jpg file for Isadora but you must use it (or another one) as a texture in the 3d programm for the video texture to work. If you don't have the jpg file in the same folder as the 3ds file, you will get an error message in Isadora. Don't care and go ahead. If you have the JPG file, it will no longer be visible afterwards.

column.zip