Assumptions
The Image Aquisition System will be a payload on the BenchBot, and can rely on the BenchBot meeting its stated requirements.
Bench Bot v3 Concept Design - BenchBot - Confluence (atlassian.net)
This will be mounted to the end effector of an X, Y, Z gantry on the new BenchBot.
The BenchBot will be able to position this system to an accuracy of +/- 1 cm.
This system will request positions from the BenchBot and can trust it was accurately reached.
Success metrics
Goal: Automated high throughput collection of high resolution images and associated metadata.
Objectives:
Collect high resolution images in an automated and systematic manner.
Collect environmental metadata.
Track metadata corresponding to each image.
Automate data upload.
Obtain camera position/orientation relative to grid.
Good user experience.
Table of Contents
Introduction
Image Quality
IQ.1.0 - Image quality
IQ.2.0 - Plant size
IQ.3.0 - Minimize adjustments
IQ.4.0 - Visual feedback
Sensor
S.1.0 - Cage
S.2.0 - Power
S.3.0 - Mounting to Gantry
S.2.0 - Image throughput (edge)
S.2.0 - Image throughput (cloud)
Image Capture
IC.1.0 - Y slider
Speed and Throughput
ST.1.0 - Image Capture
ST.2.0 - Motion
Metadata
M.1.0 - Species ID
M.2.0 - Weather info
M.3.0 - Weather station
M.4.0 - Incident light sensor
M.5.0 - RTK
M.6.0 - Position information
M.7.0 - IMU data
Requirement Workflow
Introduction
The purpose of BB 3.0 is to collect large amounts of high throughput image data in semi-controlled outdoor nursery conditions of agriculturally relevant weeds, cover crops, and cash crops. Images are collected in such a way that they can be semi-automatically annotated, enabling the development of a comprehensive image repository. The image repository will serve as a valuable resource for computer vision researchers and professionals in the field.
Depth of field considerations to keep in mind wrt need for z-axis camera movement
With a set of base assumptions, the produced depth of field is 16.9 cm, corresponding to a far and near limit at 1.74 m and 1.57 m respectively, assuming that the focus is set for a distance of 1.65 m. This is based on a pixel size of 3.76 um in a full frame sensor setup at 61 megapixel, a 55mm lens, an aperture of F13 and a distance from the camera to the plant of 1.65 meter. As the aperture is physically decreased, the depth of field in increase, at the cost of decreased optical resolution due to diffraction. F13, is what I, Søren, would characterize as the sweet-spot between depth of field and a negligible loss of optical resolution due to diffraction. Sources for depth of field and diffraction calculations. With this in mind, if the lens is not auto-focusing, the camera should to be controlled in the z-axis with a resolution of 3-5 cm.
Flash consideration to keep in mind
The flash should be dominant relative to natural sunlight. As sunlight can reach an intensity of 98,000 lux, the flash should ideally fire with at least twice the intensity.
The alienbees ABR800 has an output of 14000 lumenseconds with a flash duration (t.5) of 1/2000, meaning that 3/4 of the light has been fired after 1/2000 seconds. Based on this, the ABR800 has a light output of 21,000,000 lumen. Assuming a light spread of 10 m2, that results in 2,100,000 lux, or 21 times the maximum sunlight intensity for a short interval. If limited to a shutter speed of 1/200 due to a rolling shutter sensor, that number is down to 2,800,000 lumen and 280,000 lux, or three times the sun intensity.
Our current Godox AR400 ring flash has an output of approximately 8500 lumenseconds with an unknown flash duration. However, assuming that the same numbers apply, we have: 1,270,000 lux, or 13 times the maximum sunlight intensity for a short interval. If limited to a shutter speed of 1/200 due to a rolling shutter sensor, that number is down to 1,700,000 lumen and 170,000 lux, or 1.7 times the sun intensity.
Image Quality Requirements
Id | Requirement name | Description | Category | Allowable Limits | Status | Solution |
---|---|---|---|---|---|---|
IQ.3.0 | Automation | Shall minimize day to day adjustments during data acquisition and postprocessing. | Automation | |||
Color checker | Shall tag the color checker image | Automation | ||||
IQ.2.1 | Plant size | Shall reliably support plant sizes with a planar radius of 30 cm at soil level, centered at each pot. | Data | |||
Could support multiple sensors simultaneously | Data | |||||
Images shall overlap | Data | 65% | ||||
IQ 3.1 | File architecture | Shall create a folder per data collection day and save files in such folder | Data | |||
IQ.2.0 | Plant size | Shall support plant sizes with a height ranging from 0 cm to 40 cm above the pot soil | Data | |||
Internet connection | Good to have | |||||
Global shutter | Assuming a shutter speed of | Image Quality | ||||
Rolling shutter | Image Quality | |||||
Flash (Roller shutter) Intensity | Image Quality | |||||
Flash (Roller shutter) Intensity | ||||||
Auto focus | Camera shall have auto focus | Image Quality | TRUE/FALSE | |||
Automatic manual focus | If auto focus FALSE then this one is needed | Image Quality | z positional accuracy of 3-5 cm | |||
1.1 | Image quality | Image noise must be kept to a minimum by using to the camera’s base ISO while still have an acceptable exposure histogram | Image Quality | ISO=BASE (100 for Sony full frame sensors) | ||
1.2 | Relative Image Resolution | The camera should provide a soil-level Ground Sample Distance (GSD) of minimum 8 pixels per mm. | Image Quality | 7-9 pixels per mm (emergence) | ||
1.3 | MP | Image Quality | ||||
1.4 | Sensor size | Full frame | Image Quality | |||
1.6 | Sensor type | CMOS | Image Quality | |||
1.7 | Pixel size | Image Quality | ||||
1.8 | File type | Shall output RAW and JPG files | Image Quality | |||
Species ID | Shall provide species ID for each pot in X, Y position | Metadata | ||||
Weather info | Shall have accurate local weather data information for each run | Metadata | Captured from on site weather station | |||
Light information | Shall provide incident light information per image | Metadata | Sensor positioned near camera | |||
Camera position | Shall provide absolute and relative camera position and orientation | Metadata | +/- 1 cm +/- 1o | |||
Image metadata | Shall provide ISO and Shutter Speed | Metadata | ||||
Shall allow the user to change camera settings | Not a general requirement | |||||
Image throughput | Shall be able to capture images of 500 pots in less than 4 hours (500 images) | Speed and Throughput | ||||
Data transfer speed | Shall be such that does not jeopardize the minimum required image throughput. | Speed and Throughput | ||||
IQ.4.0 | Visual feedback | Should provide visual feedback to the user for manual inspection of errors during data collection | User Interaction | |||
Shall allow the user to enter metadata | User Interaction | |||||
Shall allow the user to share data | User Interaction | |||||
Shall allow the user to trigger camera independently | User Interaction | |||||
Auto focus |
Emergent design properties
Camera position | RTK | Shall have individual images tagged with RTK position information (x,y,z) |
Camera position | IMU | Shall have IMU data for camera position at each capture event |
Weather information | Weather station | |
Sensor Requirements
Key | Summary | Specification | Allowable Limits | Status |
---|---|---|---|---|
S.1.0 | Auto focus | should be designed to | ||
S.2.0 | ||||
S.3.0 | ||||
S.4.0 | ||||
Image Capture Requirements
Key | Summary | Specification | Allowable Limits | Status |
---|---|---|---|---|
IC.1.0.0 | Y position | Shall have the ability of the Y camera slider to stop in certain positions | ||
Speed and Throughput Requirements
Key | Summary | Specification | Allowable Limits | Status |
---|---|---|---|---|
ST.1.0.0 | Image throughput | |||
ST.2.0.0 | ||||
Data transfer speed |
Metadata Requirements
Key | Summary | Specification | Allowable Limits | Status |
---|---|---|---|---|
M.1.0 | Species ID | Shall provide species ID for each pot in X, Y position | ||
M.2.0 | Weather info | Shall have weather data information for each run captured from weather station | ||
M.3.0 | Weather station | Shall have a weather station | ||
M.4.0 | Light sensor | Shall have incident light sensor positioned near camera | ||
M.5.0 | RTK | Shall have individual images tagged with RTK position information (x,y,z) | +/- 3 cm | |
M.6.0 | IMU | Shall have IMU data for camera position at each capture event | ||
M.7.0 |
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