GRASSHOPPER TUTORIAL 04 IMAGE SAMPLING - ex-Lab

GRASSHOPPER TUTORIAL 04
IMAGE SAMPLING
www.exlab.org

IDEA

MANIPULATION FOR TRANSFORMATION
Using a series of data manipulations, colour information from an
image is used to inform a complex geometric outcome.

TUTORIAL - IMAGE SAMPLER GH ID 1/1
GWYLL JAHN- 09072011

EXERCISE EX 1/4
THE COLOUR CODING FROM THE
STRUCTURES DEMO FILE WILL BE USED
THROUGHOUT THIS DEFINITION

REFERENCE A SERIES OF POINTS FROM
RHINO (THESE WILL BE ARRAYED TO MAKE A
GRID)

TO ENSURE ALL POINTS ARE COPIED
CORRECTLY, WE MUST GRAFT THE
COMPONENTS SO THAT EACH ITEM IS ON ITS
OWN BRANCH OF DATA

WE THEN ALSO SIMPLIFY THE PATH
STRUCTURE (FROM {0;0} TO {O})

THESE POINTS WILL THEN BE PASSED TO THE
MOVE COMPONENT

TUTORIAL - IMAGE SAMPLER GH
GWYLL JAHN- 09072011

EXERCISE EX 2/4
INSERT A SERIES COMPONENT

MAKE THE DATA FROM THE SERIES
COMPONENT INTO MAGNITUDE VECTORS IN
THE Y-AXIS DIRECTION (OUR INITIAL POINTS
WERE ALONG THE X-AXIS)

THESE VECTORS ALSO NEED TO HAVE
ADDITIONAL PATH STRUCTURE REMOVED
WITH THE FLATTEN COMPONENT

WE NOW WANT TO MAP THESE POINTS TO
AN IMAGE IN ORDER TO CREATE A NEW (AND
VARIABLE) GEOMETRY AT EACH POINT THAT
CORRESPONDS TO THE BRIGHTNESS OF THE
PIXEL IN THE IMAGE.
DECOMPOSE THE POINTS TO FIND THE
INFORMATION FOR EACH CARTESIAN AXIS

WE WANT TO SAMPLE AN IMAGE WITH A
DOMAIN BETWEEN 0 AND 1, SO WE NEED
TO REMAP THIS DATA WITHIN A MATCHING
DOMAIN. PASS THE INITIAL DATA LIST TO A
REMAP COMPONENT

TUTORIAL - IMAGE SAMPLER GH
GWYLL JAHN- 09072011

EXERCISE EX3/4
THE TARGET DOMAIN IS 0 TO 1.
THIS CAN BE DONE WITH A ‘DOMAIN
COMPONENTS’ COMPONENT, OR A PANEL

FLATTEN THE INITIAL X AND Y COORDINATE
DATA IN ORDER TO FIND THE EXTREMA (IN
THE NEXT STEP). IF WE DO NOT FLATTEN,
GRASSHOPPER FINDS THE EXTREMA PER
BRANCH

FIND THE ‘BOUNDS’ OF THE FLATTENED
DATA, THE LARGEST AND SMALLEST ITEMS

THIS IS PASSED TO THE REMAP COMPONENT
AS THE SOURCE DOMAIN

THIS INFORMATION IS USED TO REMAP THE
COORDINATES FROM THE UNFLATTENED
POINTS. THIS ALLOWS US TO KEEP THE
ORIGINAL PATH STRUCTURE

TUTORIAL - IMAGE SAMPLER GH
GWYLL JAHN- 09072011

EXERCISE EX 4/4
USING THE IMAGE SAMPLER SETTINGS
(RIGHT-CLICK) TO REFERENCE AN IMAGE
FILE. ENSURE THE DOMAIN FOR X AND Y
DIRECTIONS ARE SET BETWEEN 0 AND 1

ENSURE THE IMAGE IS ‘CLAMPED’ AND
SELECT ‘VALUE’ (BRIGHTNESS) AS THE
FILTER.
THE CORRESPONDING POINTS ON THE
IMAGE ARE SAMPLED FOR THIS COLOUR
INFORMATION AND RETURNED

THE IMAGE SAMPLER OUTPUTS VALUES
BETWEEN 0 AND 1 SO WE HAVE TO USE A
FUNCTION TO SCALE THESE VALUES UP OR
DOWN TO SOMETHING WITH REAL WORLD
DIMENSIONS

FINALLY, BECAUSE OUR PATH STRUCTURE
IS UNCHANGED, WE CAN SIMPLY FIND
THE ORIGINAL GRID OF POINTS (PRIOR TO
REPARAMATERISATION ETC) AND USE THE
VALUES FROM THE IMAGE SAMPLER TO
CONTROL THE RADII OF A CIRCLE AT EACH
POINT

TUTORIAL - IMAGE SAMPLER GH
GWYLL JAHN- 09072011