Cylindrical Projection

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Cylindrical Projection by Jens Kafitz










Cylindrical Projection will project your image using cylindrical texture coordinates to avoid seams and ugly blending

on objects such as wheels, trees, barrels etc.


Video


A feature presentation for an older version of this node can be found here



An updated video, how to position the Projection in 3D Space can be found here


How to position the Projection in 3D Space


Positioning using Locators


Step by Step:


For easiest positioning turn on the 'Debug Pattern' Checkbox under the Texture Map Group of the Cylindrical Projection Node


  1. Go to 'Projection Pivot' Group in the Node's Properties.


  1. On the Projection Pivot Option click the '+' button to add a new locator

or choose an existing one from the dropdown



  1. A new locator will be added to your mari scene. You can also see this new locator in the Object Palette.



The position of this locator marks the pivot of the projection which is always located at the

'cap' centre of the cylindrical projection


Cylinder Pivot is defining the center point of the 'cap' of your projection:


  1. Next go to the 'Projection Rotation' Group in the Node's Properties


  1. Add a new locator there as well or (recommended) choose the same locator as you have set for your Projection Pivot


  1. In either Projection Pivot or Projection Rotation click on the Transform button next to the '+'.



  1. Mari will switch from your current object over to the 'Locator' Object in the Object Palette and activate the 'Transform Selected Option' Tool.

A locator gizmo will become visible in the viewport (you might have to look at your world centre to see it, if your object is positioned away from the grid)


The Locator Transformation Gizmo visible in your viewport


  1. Move the Locator to where you want the pivot to be.


The Locator Transformation Gizmo position at the bottom centre of the object



  1. Rotate the Projection into place. If you feel like the cylinder projection is facing the wrong direction, tick/untick the Mirror option.

Once you are happy with the general orientation you can use the Extra Attributes (Pivot Rotation) to make very precise adjustments.




Tip: Lock your object


When the Locator Gizmo is over your object it is very easy to 'miss the click' on the rotation ring

and activate the object instead which will result often in inadvertently moving the object around


Consider locking your object via the object palette to avoid moving it by mistake.




The aligned projection


  1. Turn off the Debug Pattern Option and plug in the map you want to project



Manual Positioning




Video


A full video of the manual positioning process described here is available on Vimeo





Step by Step:


  1. Position your model in your viewport so that you are looking along the length of your future cylindrical projection


  1. Generate your Cylindrical Projection Node and open group 'Extra Attributes (Pivot Translation)'.

Ensure that the Cylindrical Projection Node sits above any LUT applying Node such as sRGBtoLinar.

You can move the Cylindrical Projection Node back under it once you completed this basic orientation step-by-step.


Cylinder Pivot is defining the center point of the 'cap' of your projection:


  1. Turn on the 'Display Object Position as Color Value' checkbox found under the  'Extra Attributes (Pivot Translation)' Group

This will show the object position X/Y/Z converted to an RGB Value.

Since these positional values are likely over 1.0, your object will go most likely completely white.


  1. Open the Pixel Analyzer Palette via VIEW / PALETTES


  1. In your lower right hand corner of your Mari Main Window ensure that 'HDR' is active.

If the icon displays 'LDR' click on it to switch to 'HDR'. This ensures that values above 1.0

can be sampled in the viewport.




  1. Switch to your 'Color Picker' Tool and on your object click at the point you want to represent the center pivot

of your projection



  1. Transfer the RGB Values from your Pixel Analyzer Palette into X,Y and Z Offset of the Cylindrical Projection and turn off

'Display Object Position as Color Value' checkbox. You are now free to move the Projection Node anywhere you want in the

Layerstack (including below a LUT Node such as sRGBtoLinear)



  1. Scroll to the top of the Cylindrical Projection Node and activate 'Debug Pattern'.

This will show you a UV Check pattern made out of squares to help you adjust repeat and rotation.


  1. Open the Group  'Extra Attributes (Pivot Rotation)' in the Cylindrical Projection Node and adjust the rotation

depending on your models necessities. By default the Cylindrical Projection is generated in a 90 degree angle

to the grid (standing cylinder).




Tip:


Set Slider 'Length' to a small value to help you identify which axis is supposed to be what orientation during rotation.



  1. Your Projection should now be oriented correctly and you can turn off the 'Debug Pattern' and plug in a texture map.



Node Overview




Node Properties


Texture Map


Overrides the Texture Map and shows a Debug Pattern with squares.

This is useful to orient your projection and adjust tiling values (repeat u/v)


The image to be projected. Transparency is supported.


A rotation on the 'Texture Map'  in local space of the map itself


A translation/offset on the 'Texture Map'  in local space of the map itself. This is useful to slide the texture along the cylindrical projection.


Cylinder Dimension


When adjusting the 'Length' parameter of the projection the texture repeat changes by default.

With Lock UV Scale turned on adjusting texture repeat will compensate for changes in  'Length'


The Length/Height of your cylindrical projection





Changing Slider Range


If you feel that your length (or any other positional value) is changing too fast even with small

slider changes, go to the 'Transform Helpers' Group in the Cylindrical Projection Node

and set the multiplier lower !



The radius of your cylindrical projection determines where the projection will be clipped.



Different Radius on a projection:



Squashes the profile of the cylinder that is projecting. This is useful to redistribute features on objects that are not

100 % cylindrical to avoid texture stretching or deliberately introduce it.


UV Size


Texture Repeat around the circumference of the cylinder


Texture Repeat along the length of the cylinder


Uniform Texture Repeat multiplier for RepeatU and RepeatV


Projection Pivot


Specifies the location in space of the base pivot of the projection.

Please refer to How to Position the Projection in 3D Space for more detailed information.


In addition to the translation options here you can fine tune the position using the attributes under the

'Extra Attributes (Pivot Translation)' Group


Projection Rotation


Sometimes after positioning your cylinder pivot, the cylinder might be 'standing on the pivot' facing the wrong direction.

Instead of rotating the cylinder again, simply tick or untick Mirror to tip the cylinder on its head.


Specifies the orientation in space of the of the projection.

Please refer to How to Position the Projection in 3D Space for more detailed information


In addition to the rotation options here you can fine tune the position using the attributes under the

'Extra Attributes (Pivot Rotation)' Group

Pie Clip


Plane Slice will cut the texture projection from either start or end of the cylinder.

The base of the cylinder (pivot) determines which side Plane Slice Start is on.


A secondary offset on the main slider with a finer granularity on the slider for fine adjustments





Pie Slice will slice the Projection around the circumference of the cylinder


A secondary offset on the main slider with a finer granularity on the slider for fine adjustments




Extra Attributes (Pivot Translation)





Extra Attributes vs. Locators


Please note the options below are working on top of any locators created, meaning that by modifying the extra attributes the locator position will no longer be 100% representative of your cylinder pivot position



Shows your objects position values (X,Y,Z) as RGB Values so they can be sampled with the Pixel Analyzer Tool.

Refer to How to position your Projection in 3D Space for more details.


The X, Y and Z Position of your Cylinder Pivot relative to its original position (world 0 or locator position). These values can be obtained by sampling the position with the Pixel Analyzer Tool


A secondary offset on each main slider with a finer granularity on the slider for precision positioning



Extra Attributes (Pivot Rotation)


Rotates the cylinder around the pivot of the projection.


A secondary rotation offset on each main slider with a finer granularity on the slider



Extra Attributes (Slider Multipliers)


Depending on your scene size some of the default slider ranges might be too large.

The following multipliers will help you compensate for very large or very small object sizes.



A multiplier on Length+Radius, the fine Offset Controls of Cylinder Pivot & Rotate Cylinder (not the main sliders !)

as well as the the fine Offset Controls on the Clipping Options (not the main sliders).


If any of the sliders below are used, the result will be multiplied.


A multiplier on Length & Radius Controls.


A multiplier on the fine offset controls of Cylinder Pivot & Rotate Cylinder (not the main Offset sliders ! )


A multiplier on the fine offset controls of Projection Clipping Options (not the main Clip sliders ! )



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