Hologram Pi-ramid - Project complete!

1 Jun 2019

I have reached the conclusion of the Picasso Challenge and I must say it has be quite a challenge journey!. I enjoyed so much working on this project where I learned tons of new things and it gave me the opportunity to stay in touch with awesome members of the Element14 community. I'd like to take this opportunity to present one more Hologram demo, hope you enjoy it!.

Warning: The following video contains loud sounds

Before heading to the conclusion of the project, I'd like to include a summary of useful resources.

Bill of Materials

Complete list of materials:

Electronics

1 x Raspberry Pi 3B+
1 x Raspberry Pi Touch Display
1 x Camera Module V2
5 x WS2812B Addressable RGB LED
5 x 0.1µF, 6.3V Ceramic Capacitor, 0603[1608]

1 x 0.1" pitch (2.54 mm) Female Header: 1x4-Pin, Straight

1 x 0.1" pitch (2.54 mm) Male Header: 1x4-Pin, Straight

Stranded Wire: Various colors, 26/28 AWG
Heat-shrink tube

Assembly

2 x #2 x 3/8" Slotted Round Head Screws

4 x #2 x 1/4" Slotted Round Head Screws (to secure the Camera to the 3D printed frame)

6 x #5-40 x 3/8" Socket Head Cap Screws
2 x #6-32 x 2" Socket Head Cap Screws

4 x M3-0.50 x 4mm Socket Head Cap Screws (to secure the Touchscreen to 3D printed frame)

Other

Small piece of Acrylic (Plexiglass)
Methylene chloride (dichloromethane or DCM)
PLA
Black paint (Matte finish)
Hot glue

3D Designs

All technical drawings I've used are available here. All the STL files required have been attached to this blog entry.

3-D Print settings

Settings used for all 3D printed parts:

Printer: Creality CR-10S
Material: PLA Blue-denim
Infill: 15%, triangles
Adhesion: Brim
Supports: No
Layer height: 0.2mm
Nozzle size: 0.4mm

The entire 3D model can be viewed at Myhub on Autodesk.

Acrylic Pyramid

Three pieces of Acrylic must be cut to build the Plexyglass pyramid -perhaps the most important non-electronics piece of the project. Then such pieces are welded together with Methylene chloride (dichloromethane or DCM)

Technical information

Electronics Assembly

The custom made electronics assembly is fairly simple, diagram below is perhaps the most important resource in this area:

All the custom made electronics designs are attached to this blog entry as well.

Source code

The source code is very extensive as I have explained mainly how to display video with Python and OpenCV -an important piece needed for this project to thrive. Also I have explained in detail how to handle the Addressable RGB LEDs with Python.

In this summary, I'm adding one last piece of code; how I managed to show a fire hologram and enhanced the fire effects with Addressable RGB LEDs all in one script:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# Displays a video and enhances flames effect with WS2812B Addressable LEDs
#
# Luis Ortiz - luislab.com
# May 19, 2019

import cv2
import board
import random
import neopixel

print("OpenCV", cv2.__version__) # Video

winName = "Element14"
vidFile = "e14Fire.mp4"

vid = cv2.VideoCapture(vidFile)
if not vid.isOpened():
    print("Error: Could not open ", vidFile)
    exit()

vidFPS = vid.get(cv2.CAP_PROP_FPS)
waitPerFrame = int(1000 / vidFPS)        # in milliseconds
print("fps:", vidFPS)
print("Time between frames:", waitPerFrame, "ms")

cv2.namedWindow(winName, cv2.WND_PROP_FULLSCREEN)
cv2.setWindowProperty(winName, cv2.WND_PROP_FULLSCREEN, cv2.WINDOW_FULLSCREEN)

numLEDs = 5
ledStrip = neopixel.NeoPixel(board.D18,
                             numLEDs,
                             brightness=0.015,
                             auto_write=True)
R = G = B = 0

try:
    while True:
        retVal, frame = vid.read()

        if retVal:
            cv2.imshow(winName, frame)

            #Yellow channels (with slightly random red - Front LEDs)
            R = G = random.randint(100, 255)
            B = random.randint(0, 50)
            ledStrip[2] = (R, int(G * 0.8), B)

            R = G = random.randint(100, 255)
            B = random.randint(0, 50)
            ledStrip[3] = (R, int(G * 0.8), B)

            R = G = random.randint(100, 255)
            B = random.randint(0, 50)
            ledStrip[4] = (R, int(G * 0.8), B)

            #Pure Yellow channels (top LEDs)
            R = G = random.randint(150, 255)
            B = random.randint(0, 20)
            ledStrip[0] = (R, G, B)

            R = G = random.randint(150, 255)
            B = random.randint(0, 20)
            ledStrip[1] = (R, G, B)

        else:
            vid.set(cv2.CAP_PROP_POS_FRAMES, 0) #End of video

        if cv2.waitKey(waitPerFrame) == 27: # ESC to quit
            print("Aborted at frame:", vid.get(cv2.CAP_PROP_POS_FRAMES))
            break

finally:
    vid.release()
    cv2.destroyAllWindows()
    ledStrip.fill((0, 0, 0))
    print("Bye!")

In order to keep things simpler I have not included the motion detection.

Blogs in this series

My Picasso Design Challenge entries

If you made it this far, thanks for reading. Your thoughts and comments are always appreciated. A big thanks to Element14 and all the community members who showed up in any way.

Luis

Displaying Holograms