2 : When the user calls the set_image_encoding service to use 16-bits encoding, the driver will check first for the availability of the requested 16-bits encoding to set it, when the requested 16-bits image encoding is not available, then the driver will check the availability of the equivalent 12-bits encoding to set it. When both 16-bits and 12-bits image encoding are not available then an error message will be returned.

Often, your microscope will have at least three objective lenses on a rotating disc, each with a different magnification level. If you find your current lens lacking, it's easy to switch to one of the others. Objective lenses with higher magnification have shorter focal lengths, or less space between the lens and the surface of the subject. Since depth of field decreases as magnification increases, those wanting a broader field of view should stick to shorter lenses. For example, if your current objective lens has 100x magnification but you need a wider field of view, you'll want to switch to a lens with lower magnification, such as 40x.

Your objective lens isn't just for increasing the size of your subject; it can also provide better resolution. For example, achromatic lenses contain two smaller lenses (convex and concave) that are used to limit the refracting light of your subject, and phase-contrast lenses use phase plates to pick up miniscule changes in wavelength amplitude, making moving subjects easier to observe. Lenses like these help reduce ghost images so that the real image is projected to your eyepiece.

auto_flash_line_2 (not for the blaze) Flag that indicates if the camera has a flash connected on line 2, which should be on exposure. Only supported for GigE cameras. Default: true.

The official pylon ROS2 driver for Basler GigE Vision, Basler USB3 Vision and Basler blaze 3D cameras (Humble Hawksbill)

brightness_continuous (not for the blaze) Only relevant, if 'brightness' is set: The brightness_continuous flag controls the auto brightness function. If it is set to false, the brightness will only be reached once. Hence changing light conditions lead to changing brightness values. If it is set to true, the given brightness will be reached continuously, trying to adapt to changing light conditions. This is only possible for values in the possible auto range of the pylon API which is e.g., [50 - 205] for acA2500-14um and acA1920-40gm.

Figuring out the total magnification power of your microscope is easy: just multiply the power of your objective lens by your ocular lens. For instance, if your eyepiece has 10x magnification and you're using a low-power lens (10x), you have 100x magnification in total. Switch to your scanning lens (4x), and magnification becomes 40x. It's important to keep in mind that the ocular lens and objective lens total magnification is ultimately what you're viewing. If you were viewing your subject through a single lens, then that lens would have to be extremely powerful to match what you can easily get with both. Therefore, one lens isn't nearly as effective without the other.

auto_exposure_upper_limit (not for the blaze) The exposure search can be limited with an upper bound. This is to prevent very high exposure times and resulting timeouts. A typical value for this upper bound is ~2000000us. Beware that this upper limit is only set if startup_user_set is set to Default.

grab_strategy (not for the blaze) Camera grab strategy: 0 = GrabStrategy_OneByOne / 1 = GrabStrategy_LatestImageOnly / 2 = GrabStrategy_LatestImages

auto_flash (not for the blaze) Flag that indicates if the camera has a flash connected, which should be on exposure. Only supported for GigE cameras. Default: false.

If your network adapter supports jumbo frames, you set the adapter's MTU to 8192 as described above. In order to take advantage of the adapter's jumbo frame capability, you must also set the packet size used by the camera to 8192.

It is not possible to count correctly the number of subscribers to the image_raw and image_rect topics because of a known issue with the function CameraPublisher::getNumSubscribers. That is why this image_common package, fixing this issue, needs to be cloned and compiled together with the pylon_ros2_camera_node.

Allied Vision

Depending on the camera model, it is possible to grab one or several images or 3d data sets (3d point cloud, intensity, confidence, depth map, depth color map) through the dedicated action with user-specified parameters (e.g., exposure time, brightness value, etc.). Refer to the action definitions to get more information.

In contrast, your microscope's eyepiece will usually have only one ocular lens, though you can usually swap the eyepiece as well. The standard magnification level of the ocular lens is 10x, but there are stronger ones available. When selecting an eyepiece, you should think about eye relief, or the required distance between your eyes and the lens. Eyepieces with large eye relief give you some space, while those with small eye relief require you to be up close.

Acquisition from a specific camera is possible by setting the device_user_id parameter. If no specific camera is specified, the first available camera is connected automatically.

Acquisition images are published through the [Camera name]/[Node name]/[image_raw] topic, only if a subscriber to this topic has been registered. To visualize the images, rqt can be used. Add an image viewer plugin through thanks to the contextual menu (Plugin -> Visualization -> Image View) and select the [Camera name]/[Node name]/[image_raw] topic to display the acquired and published images. The 3d point clouds acquired by the blaze can be visualized thanks to rviz2.

auto_flash_line_3 (not for the blaze) Flag that indicates if the camera has a flash connected on line 3, which should be on exposure. Only supported for GigE cameras. Default: true.

camera_frame The tf2 frame under which the images were published. ROS2 provides a library called tf2 (TransForm version 2) to manage the coordinate transformations between the different frames (coordinate systems) defined by the user and assigned to the components of a robotics system.

If you hot-swap the camera with a different camera with a non-compatible pixel encoding format (e.g., mono and color cameras), you need to restart the ROS system to replace the encoding value or replace the rosparam directly by setting the image_encoding parameter. e.g.,: rosparam set /pylon_camera_node/image_encoding "mono8"

Everyone knows that microscopes are a crucial tool in science, but few realize how versatile and adaptable they can be. Thanks to the variance in lenses, microscopes can serve all kinds of purposes for all kinds of people, from the doctor identifying cancer cells to the child wanting to get a closer look at their favorite bug. Once you know how all of the optical elements work together, like the ocular lens vs objective lens, it's easy to maximize the efficiency of your microscope.

With pylon 7.5.0, if the pylon viewer does not start, this is due to a Qt dependency missing. Try installing the xcb-cursor0 library with the following command: sudo apt install libxcb-cursor0. If it does not solve your issue, try starting the pylon viewer from the bin directory of pylon: cd /opt/pylon/bin/ && ./pylonviewer. Report then the error message to the pylon support team.

Beware that some parameters implemented by the driver, like for instance the parameter startup_user_set, can be set through 1. the pylon_ros2_camera_wrapper/config/default.yaml user parameter file, 2. the pylon_ros2_camera.launch.py driver launch file, and 3. the command line arguments of the launch command to start the driver. A parameter value set as an argument of the launch command to start the driver will overwrite the value set in the driver launch file itself, that will overwrite the value set in the user parameter file.

white_balance_ratio_red & white_balance_ratio_green & white_balance_ratio_blue (not for the blaze) Camera white balance ratio.

There are many other kinds of objective lenses out there, so you have no shortage of options. Do some research and find out which lens best suits your needs and goals.

The pylon node defines the different interface names according to the following convention: [Camera name (= my_camera or my_blaze by default)]/[Node name (= pylon_ros2_camera_node)]/[Interface name] The camera and the node names can be set thanks respectively to the camera_name and node_name parameters.

exposure_search_timeout (not for the blaze) The timeout while searching the exposure which is connected to the desired brightness. For slow system this has to be increased.

Note: The packages are built in Release by default. The build type can be modfied by using the --cmake-args flag (for instance colcon build --symlink-install --cmake-args=-DCMAKE_BUILD_TYPE=Debug).

Starting the pylon_ros2_camera_node starts the acquisition from a given Basler camera. The nodes allow as well to access many camera parameters and parameters related to the grabbing process itself.

This is why a microscope is such a good investment for anyone interested in science. If you want to understand and examine the world around you, there's no better tool. AmScope's selection is built to last, and we carry all kinds of objective lenses as well, so a microscope from us will serve you well for many years.

Please Note: This project is offered with no technical support by Basler AG. You are welcome to post any questions or issues on GitHub

Baslerpylon

It is easily possible to connect to a specific camera through its user id. This user id can be set through the parameter device_user_id listed in the .yaml user parameter file loaded at launch time (by default pylon_ros2_camera_wrapper/config/default.yaml). It is up to the user to create specific launch files, loading specific .yaml user parameter files, which would specify the user ids of the cameras that need to be connected. If no specific camera is specified, either because the device_user_id parameter is not set or no .yaml user parameter file is loaded, the first available camera is connected automatically.

The default trigger mode is set to software trigger. This means that the image acquisition is triggered with a certain frame rate, which may be lower than the maximum camera frame rate. The maximum camera frame rate can be reached when running a camera in a free-run or a hardware trigger mode.

If the calibration is valid, the rectified images are published through the [Camera name]/[Node name]/[image_rect] topic, only if a subscriber to this topic has been registered.

gain (not for the blaze) The target gain in percent of the maximal value the camera supports. For USB cameras, the gain is in dB, for GigE cameras it is given in so called 'device specific units'.

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While it may initially seem redundant to have two separate lenses in your microscope, they do far more together than they ever could on their own.

frame_rate The desired publisher frame rate if listening to the topics. This parameter can only be set once at start-up. Calling the GrabImages-Action can result in a higher frame rate.

Some classes includes in their constructor the following command, commented by default: rcutils_ret_t __attribute__((unused)) res = rcutils_logging_set_logger_level(LOGGER_BASE.get_name(), RCUTILS_LOG_SEVERITY_DEBUG); Uncomment it to display on your terminal more detailed debug information.

If the camera image acquistion is triggered by sofware trigger (default setting), then it is not possible to get the maximum frame rate, because the image acquisition is sequentially triggered, which is not overlapping then. Several possible solutions are mentionned and tested in issue #21, #28, #29, #81, #116, #147, and #200. Please refer to them for more information.

binning_x & binning_y (not for the blaze) Binning factor to get downsampled images. It refers here to any camera setting which combines rectangular neighborhoods of pixels into larger "super-pixels." It reduces the resolution of the output image to (width / binning_x) x (height / binning_y). The default values binning_x = binning_y = 0 are considered the same as binning_x = binning_y = 1 (no subsampling).

If you are working with the pylon Viewer application, you can set the packet size by first selecting a camera from the tree in the "Device" pane. In the "Features" pane, expand the features group that shows the camera's name, expand the "Transport Layer" parameters group, and set the "Packet Size" parameter to 8192. If you write your own application, use the camera API to set the PacketSize parameter to 8192.

brightness (not for the blaze) The average intensity value of the images. It depends the exposure time as well as the gain setting. If 'exposure' is provided, the interface will try to reach the desired brightness by only varying the gain. (What may often fail, because the range of possible exposure values is many times higher than the gain range). If 'gain' is provided, the interface will try to reach the desired brightness by only varying the exposure time. If 'gain' AND 'exposure' are given, it is not possible to reach the brightness, because both are assumed to be fix.

image_encoding (not for the blaze) The encoding of the pixels -- channel meaning, ordering, size taken from the list of strings in include file sensor_msgs/image_encodings.h. The supported encodings are 'mono8', 'bgr8', 'rgb8', 'bayer_bggr8', 'bayer_gbrg8' and 'bayer_rggb8'. Default values are 'mono8' and 'rgb8'.

The system's maximum UDP receive buffer size should be increased to ensure a stable image acquisition. A maximum size of 2 MB is recommended. This can be achieved by issuing the sudo sysctl net.core.rmem_max=2097152 command. To make this setting persistent, you can add the net.core.rmem_max setting to the /etc/sysctl.conf file.

For faster USB transfers you should increase the packet size. You can do this by changing the "Stream Parameters" -> "Maximum Transfer Size" value from inside the pylon Viewer or by setting the corresponding value via the API. After increasing the package size you will likely run out of kernel space and see corresponding error messages on the console. The default value set by the kernel is 16 MB. To set the value (in this example to 1000 MB) you can execute as root: echo 1000 > /sys/module/usbcore/parameters/usbfs_memory_mb This would assign a maximum of 1000 MB to the USB stack.

Industrialcamera

gige/frame_transmission_delay (not for the blaze) In most cases, this parameter should be set to 0. However, if your network hardware can't handle spikes in network traffic (e.g., if you are triggering multiple camera simultaneously), you can use the frame transmission delay parameter to stagger the start of image data transmissions from each camera.

gige/inter_pkg_delay (not for the blaze) The inter-packet delay in ticks. Only used for GigE cameras. To prevent lost frames it should be greater than 0. For most of GigE cameras, a value of 1000 is reasonable. For GigE cameras used on single-board computer, this value should be set to 11772.

Note: The --symlink-install flag can be added to the colcon build command. This allows the installed files to be changed by changing the files in the source space (e.g., Python files or other not compiled resourced) for faster iteration (refer to the ROS2 documentation).

exposure_auto & gain_auto (not for the blaze) Only relevant, if 'brightness' is set: If the camera should try to reach and / or keep the brightness, hence adapting to changing light conditions, at least one of the following flags must be set. If both are set, the interface will use the profile that tries to keep the gain at minimum to reduce white noise. The exposure_auto flag indicates, that the desired brightness will be reached by adapting the exposure time. The gain_auto flag indicates, that the desired brightness will be reached by adapting the gain.

Install the ROS2 dependencies required by the pylon ROS2 packages: cd ~/dev_ws && rosdep install --from-paths src --ignore-src -r -y You may experience some problems with the diagnostic_updater and pcl_ros dependencies. In this case, install them by executing the following commands:

Cognex

The ros2 launch mechanism doesn't allow to access stdin through a terminal (see here and here). This is solved in this implementation by installing and using xterm to emulate a terminal with possible user interaction.

The microscope is one of the most iconic and commonly used tools in many scientific fields. We rely on these devices to observe things that are so small that they are otherwise invisible to the naked eye. To do this, the microscope makes use of both an ocular and an objective lens. If you don't know the difference, don't worry; this article will tell you everything you need to know about these two lens types and how they function together to make microscopes work.

The objective and ocular lens are found on different parts of the microscope. The ocular lens is part of the eyepiece and therefore closer to your eye as you look into the microscope. The location of the eyepiece always indicates the correct observing position at or near the top of the microscope.

For camera models other than the blaze, specific user set can be specified thanks to the startup_user_set parameter. ros2 launch pylon_ros2_camera_wrapper pylon_ros2_camera.launch.py startup_user_set:=Default or ros2 launch pylon_ros2_camera_wrapper pylon_ros2_camera.launch.py startup_user_set:=UserSet1 or ros2 launch pylon_ros2_camera_wrapper pylon_ros2_camera.launch.py startup_user_set:=UserSet2 or ros2 launch pylon_ros2_camera_wrapper pylon_ros2_camera.launch.py startup_user_set:=UserSet3

gamma (not for the blaze) Gamma correction of pixel intensity. Adjusts the brightness of the pixel values output by the camera's sensor to account for a non-linearity in the human perception of brightness or of the display system (such as CRT).

1 : 12-bits image will be remapped to 16-bits using bit shifting to make it work with the ROS2 16-bits sensor standard message.

ROS2 includes a standardised camera intrinsic calibration process through the camera_calibration package. This calibration process generates a file, which can be processed by the pylon ROS2 driver by setting the camera_info_url parameter in the pylon_ros2_camera_wrapper/config/default.yaml file (it is the user parameter file loaded by default through the driver main launch file) to the correct URI (e.g., file:///home/user/data/calibrations/my_calibration.yaml).

There are four main types of objective lenses, each with a different diameter of field of view, and therefore a different magnification level:

The following settings do NOT have to be set. Each camera has default values which provide an automatic image adjustment resulting in valid images.

The pylon_ros2_camera_node can be started thanks to a dedicated launch file thanks to the command: ros2 launch pylon_ros2_camera_wrapper pylon_ros2_camera.launch.py or ros2 launch pylon_ros2_camera_wrapper my_blaze.launch.py for the blaze Several parameters can be set through the launch file and the user parameter file loaded through it (the pylon_ros2_camera_wrapper/config/default.yaml user parameter file is loaded by default, pylon_ros2_camera_wrapper/config/my_blaze.yaml for the blaze).

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In the ROS pylon implementation, the activate_autoflash_output and set_user_output service servers are shutdowned when the connection with a camera is lost. It is not possible for now to do so with ROS2 without shutting down the whole node (see here). There is no way to overcome this issue at the moment.

downsampling_factor_exposure_search (not for the blaze) To speed up the exposure search, the mean brightness is not calculated on the entire image, but on a subset instead. The image is downsampled until a desired window hight is reached. The window hight is calculated out of the image height divided by the downsampling_factor_exposure search.

camera_info_url (not for the blaze) The CameraInfo URL (Uniform Resource Locator) where the optional intrinsic camera calibration parameters are stored. This URL string will be parsed from the CameraInfoManager.

Start the driver: ros2 launch pylon_ros2_camera_wrapper pylon_ros2_camera.launch.py or ros2 launch pylon_ros2_camera_wrapper my_blaze.launch.py to start the acquisition through the blaze.

shutter_mode (not for the blaze) Set mode of camera's shutter if the value is not empty. The supported modes are 'rolling', 'global' and 'global_reset'. Default value is '' (empty)

gige/mtu_size (not for the blaze) The MTU size. Only used for GigE cameras. To prevent lost frames configure the camera has to be configured with the MTU size the network card supports. A value greater 3000 should be good (1500 for single-board computer)

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The folder pylon_ros2_camera_wrapper/test includes different test programs. testing specific functionalities implemented by the driver. These programs are for testing purposes and should be adapted according to one's needs.

To be sure to be able to connect to a specific camera, its network configuration must be manually set through Basler's pylon IP configurator. To do so, click on the camera in the list of connected devices, select the Static IP option, set an IP Address within the same range as the one of your computer, and set the same Subnet Mask as the one from your computer.

It is possible to change the packet size by changing the default value of the mtu_size parameter in the pylon ROS2 wrapper launch file. When the camera is grabbing, it is not possible to modify this parameter.

In addition to being able to do so through the pylon Viewer provided by Basler, it is possible to set the device user id with the command: ros2 run pylon_ros2_camera_component set_device_user_id [-sn SERIAL_NB] your_device_user_id. If no serial number is specified thanks to the option -sn, the specified device user id your_device_user_id will be assigned to the first available camera. USB cameras must be disconnected and then reconnected after setting a new device user id. USB cameras keep their old user id otherwise.

AmScope exclusive ALL-IN-ONE 3D DIGITAL INSPECTION MICROSCOPE. View different angles and perspectives of objects with ease.

The GigE Vision implementation of Basler pylon software uses a thread for receiving image data. Basler pylon tries to set the thread priority for the receive thread to real-time thread priority. This requires certain permissions. The 'Permissions for Real-time Thread Priorities' section of the pylon INSTALL document describes how to grant the required permissions.

startup_user_set (not for the blaze) Flag specifying if a given user set is used when starting the camera. Can be set to Default, UserSet1, UserSet2, UserSet3, and CurrentSetting.

Many GigE network adapters support so-called jumbo frames, i.e., network packets larger than the usual 1500 bytes. To enable jumbo frames, the maximum transfer unit (MTU) size of the PC's network adapter must be set to a high value. We recommend using a value of 8192.

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The objective lens, on the other hand, looms over your subject, typically near the middle of the microscope. This is because the objective lens is responsible for gathering light reflections from your subject. It then shoots a beam of light into the microscope, which becomes an image that you observe from the eyepiece containing the ocular lens.

The Precision Time Protocol (PTP) camera feature allows you to synchronize multiple GigE cameras in the same network. It enables a camera to use the following features, if available:

For camera models other than the blaze, the camera-characteristic parameter such as height, width, projection matrix (by ROS2 convention, this matrix specifies the intrinsic (camera) matrix of the processed (rectified) image - see the CameraInfo message definition for detailed information) and camera_frame were published over the /camera_info topic. Furthermore, an action-based image grabbing with desired exposure time, gain, gamma and / or brightness is provided. Hence, one can grab a sequence of images with above target settings as well as a single image. Grabbing images through this action can result in a higher frame rate.