Add install of matplotlib to raspberry pi disk image

Had to increase the disk image size to support this.  Looks like it requires
at least 2.4 GB.  I moved it to 3 GB to give some extra buffer-- not sure
if there are any issues with this size.

Change-Id: I736ee915b72b5eadb55df270884fe6ce3ea9bef3
diff --git a/y2020/vision/rootfs/README.md b/y2020/vision/rootfs/README.md
index ee34edf..0f66864 100644
--- a/y2020/vision/rootfs/README.md
+++ b/y2020/vision/rootfs/README.md
@@ -5,13 +5,20 @@
 The default hostname and IP is pi-8971-1, 10.89.71.101.
   Username pi, password raspberry.
 
-Download 2020-02-13-raspbian-buster-lite.img (or any newer buster version)
-from `https://www.raspberrypi.org/downloads/raspberry-pi-os/` and
-edit `modify_rootfs.sh` to point to it.  Run modify_rootfs.sh to build the
-filesystem (you might need to hit return in a spot or two).
+Download 2020-08-20-raspios-buster-armhf-lite.img (or any newer buster
+version, as a .zip file) from
+`https://www.raspberrypi.org/downloads/raspberry-pi-os/` (or
+`https://downloads.raspberrypi.org/raspios_lite_armhf/images/` for
+older images), extract (unzip) the .img file, and edit
+`modify_rootfs.sh` to point to it.
+
+Run modify_rootfs.sh to build the filesystem (you might need to hit
+return in a spot or two and will need sudo privileges to mount the
+partition).
 
 After confirming the target device, deploy by copying the contents of the image
 to the SD card.
+
   `dd if=2020-02-13-raspbian-buster-lite.img of=/dev/sdX bs=1M`
 
 Use `lsblk` to find the device and make absolutely sure this isn't your hard
@@ -19,3 +26,7 @@
 
 From there, log in, `sudo` to `root`, and run `/root/bin/change_hostname.sh` to
 change the hostname to the actual target.
+
+A couple additional notes on setting this up:
+   * You'll likely need to install (`sudo apt install`) the emulation packages `proot` and `qemu-user-static` (or possibly `qemu-arm-static`)
+   * If the modify_root.sh script fails, you may need to manually unmount the image (`sudo umount ${IMAGE}`) before running it again
diff --git a/y2020/vision/rootfs/modify_rootfs.sh b/y2020/vision/rootfs/modify_rootfs.sh
index 6ebeeca..8cec075 100755
--- a/y2020/vision/rootfs/modify_rootfs.sh
+++ b/y2020/vision/rootfs/modify_rootfs.sh
@@ -2,7 +2,8 @@
 
 set -xe
 
-IMAGE="2020-02-13-raspbian-buster-lite.img"
+# Full path to Raspberry Pi Buster disk image
+IMAGE="2020-08-20-raspios-buster-armhf-lite.img"
 BOOT_PARTITION="${IMAGE}.boot_partition"
 PARTITION="${IMAGE}.partition"
 
@@ -43,7 +44,7 @@
 else
   OFFSET="$(fdisk -lu "${IMAGE}" | grep "${IMAGE}2" | awk '{print 512*$2}')"
 
-  if [[ "$(stat -c %s "${IMAGE}")" < 2000000000 ]]; then
+  if [[ "$(stat -c %s "${IMAGE}")" < 3000000000 ]]; then
     echo "Growing image"
     dd if=/dev/zero bs=1G count=1 >> "${IMAGE}"
     START="$(fdisk -lu "${IMAGE}" | grep "${IMAGE}2" | awk '{print $2}')"
diff --git a/y2020/vision/rootfs/target_configure.sh b/y2020/vision/rootfs/target_configure.sh
index f761e84..63a7378 100755
--- a/y2020/vision/rootfs/target_configure.sh
+++ b/y2020/vision/rootfs/target_configure.sh
@@ -38,6 +38,7 @@
   libopencv-videostab3.2 \
   libopencv-viz3.2 \
   python3-opencv \
+  python3-matplotlib \
   gstreamer1.0-plugins-bad \
   gstreamer1.0-plugins-base \
   gstreamer1.0-plugins-good \