I am new to LiDAR technology. From the Documentation I found that we can visualize LiDAR data using Veloview software. But my aim is to create a 3D image using .pcap file and process it further for object detection. Whole working is in Ubuntu 14.04.
Can anyone provide me a good solution?
Open 6 terminal tabs (Ctrl + Shift + t):
1st tab:
$ roscore
2nd tab (run your .pcap file):
$ rosrun velodyne_driver velodyne_node _model:=VLP16 _pcap:=/path/to file.pcap
3rd tab: (create .bag file to visualize in Rviz)
$ rosrun rosbag record -O vlp_16.bag /velodyne_packets
4th. tab: (play your .bag file just created from 3rd. tab):
$ rosbag play vlp_16.bag
5th. tab: (to convert velodyne_msgs/VelodyneScan to /Pointcloud2 and /LaserScan topic to visualize in Rviz):
$ roslaunch velodyne_pointcloud VLP16_points.launch
6th. tab: (fixed frame MUST be assigned to "velodyne")
$ rosrun rviz rviz -f velodyne
In Rviz:
To visualize /scan topic:
Displays -> Add -> By topic -> LaserScan
To visualize velodyne_points topic:
Displays -> Add -> By topic -> PointCloud2
Enjoy!
I would suggest looking into using ROS and the point cloud library. There is a lot of support for this kind of processing using those. For pulling in the data form the VLP-16 you could use this ROS package.
You may use the Point Cloud Library.
Compiling PCL is a bit tricky, but once you get it going, you can do quite a lot of point cloud analysis.
Follow the instructions here for the LiDAR HDL Grabber.
For your purpose, you will want to include the <pcl/io/vlp_grabber.h> along with the <pcl/io/hdl_grabber.h>. The vlp_grabber, basically uses the same hdl_grabber but supplies the vlp calibration parameters. Also in the main, you will want to instantiate a pcl::VLPGrabber instead of a pcl::HDLGrabber.
These few changes alone may not be enough to getting a fully functional grabber and viewer, but it is a start.
The example on PCL is for the hdl_viewer_simple.cpp but there is also a vlp_viewer.cpp also located in visualization/tools/. Check that out.
This is not an answer to fully solve your problem, but provide a path to a solution if you want to use PCL.
Related
I am trying to create snapshots from a video stream using the "scene" video filter. I'm on Windows for now, but this will run on Linux I don't want the video output window to display. I can get the scenes to generate if I don't use the --vout=dummy option. When I include that option, it does not generate the scenes.
This example on the Wiki indicates that it's possible. What am I doing wrong?
Here is the line of code from the LibVLCSharp code:
LibVLC libVLC = new LibVLC("--no-audio", "--no-spu", "--vout=dummy", "--video-filter=scene", "--scene-format=jpeg", "--scene-prefix=snap", "--scene-path=C:\\temp\\", "--scene-ratio=100", $"--rtsp-user={rtspUser}", $"--rtsp-pwd={rtspPassword}");
For VLC 3, you will need to disable hardware acceleration which seems incompatible with the dummy vout.
In my tests, it was needed to do that on the media rather than globally:
media.AddOption(":avcodec-hw=none");
I still have mainy "Too high level or recursion" errors, and for that, I guess you'd better open an issue on videolan's trac.
I'm currently working on a small raster refining tool. The goal is, to have a simple CLI tool, to compute tiles from a georeferenced source raster and create a corresponding index.shp. For this I'm using python 3.7 and gdal. The tool runs smoothly and generates the expected tiles and shapefile, but it gets rid of the projection, which is stored in the source raster. Qgis defaults the newly computed tiles to EPSG 4326 while informing me about an unknown projection. The original raster is in EPSG 25832.
My Setup:
Windows 10 64 bit
Python 3.7.2
Gdal I cannot access the specific version, since gdal-config is not installed and I cannot make it work, but it is 64-bit and I installed it through the binaries provided on gisinternals.com. Windows software list says GDAL 204 MSVC 2017.
While running the script, I get error messages telling me about missing files, e.g. pcs.csv, datum.csv ellipsoid.csv and so on. This indicates that having those files, would fix my problem.
But oddly enough, I have used Osgeo4W to install, python 2.7 with gdal and it works like a charm, of course having adjusted the python parts. Tiles get calculated and stay in the projection of the source. Without any external files which specify a projection, in fact using the exact same data which is really confusing to me.
To my understanding, there is no flag or option which forces gdal to keep the projection. If have overlooked or missunderstood the docs im glad for advice.
Before anyone asks, i know that using the osgeo4w installer is obviously the easy and working solution here. But keeping in mind that python 2.7 will soon be discontinued and also using this as a chance to learn new things i wanted to build a 3.7 based tool with gdal installed on my machine
The corresponding code looks like this and does the following :
1.) Command string is build
2.) string is handed to os.system, which in turn executes accordingly
for i in range(0, width, tilelenght):
y = 0
for j in range(0, height, tilelenght):
gdaltranString = f'gdal_translate -of GTIFF -srcwin {i}, {j}, {tilelenght}, {tilelenght} {input_filepath} {output_filepath}{x}_{y}.tif'
subprocess.run(gdaltranString)
y = y+1
x = x+1
The expected result, would be a collection of functional .tif files which have the EPSG code of the source file, in this case 25832.
But as already mentioned, the projection gets lost somewhere in the process.
So,i have found the solution to my problem, without really understanding how it became an issue to begin with.
The solution was to create an user variable GDAL_DATA with the path to the projection definition files.
The weird thing is, i now have GDAL_DATA, as system variable and user variable, both pointing to the same directory.
If someone knows more about the mysterious ways of windows system variables, please share your wisdom, or the source of said wisdom.
So I am a newbie to OpenModelica. I have a bit of experience using LMS Amesim. I created my first simple model using OM and simulated it from within the OMeditor.
When I switch to the plot window, there are NO output variables to plot. That tells me that the simulation may not have run. However, no error messages popped up. When I checked the model, I found it to be fine (not overconstrained or underconstrained).
What gives? This is OM 1.14 on Linux Ubuntu 16.04.
My Modelica file is a simple 2nd order system with feedback control is available via pastebin here or may be downloaded here via google drive link
The messages that I have from the output window are:
/tmp/OpenModelica_drN/OMEdit/Feedback/Feedback -port=35318 -logFormat=xmltcp -override=startTime=0,stopTime=100,stepSize=0.2,tolerance=1e-6,solver=dassl,outputFormat=csv,variableFilter=.* -r=/tmp/OpenModelica_drN/OMEdit/Feedback/Feedback_res.csv -w -lv=LOG_STATS -inputPath=/tmp/OpenModelica_drN/OMEdit/Feedback -outputPath=/tmp/OpenModelica_drN/OMEdit/Feedback
The initialization finished successfully without homotopy method.
The simulation finished successfully.
This was a bug. Should be fixed now:
https://trac.openmodelica.org/OpenModelica/ticket/5251
I'm coding a program to do some action with webdriver and Autoit in python, I want to do two things before I start selling my code:
Add onetime activation code to my software on one PC, like to make the program works only on one pc.
Make my program able to receive updates from the internet once I add to the code some more features or correct some others.
is it possible only with Python? or what is the method statement to do it?
On client side you need use hard-disk serial or/and uuid of partition or Operational System timestamp + something to generate serial code .
On server side , you need a API to store hard disk serial to validate if this is a computer valid . And you client on load check if activaction is valid .
The second question i can't answer .
Regarding the second part of your question:
Create a text file with the latest version of your application and put it on your webserver e.g. http://download.example.com/example-app-version.txt to get and read its value later.
On your python code download and read the text (for Python 3+ use 'import urllib.request' and urllib.request.urlretrieve) when your app runs and compare it against the installed version (if statement).
E.g.
if latestVer > installedVer:
#update
else:
#application continues
I am currently creating a music player in python 3.3 and I have a way of opening the mp3/wav files, namely through using through 'os.startfile()', but, this way of running the files means that if I run more than one, the second cancels the first, and the third cancels the second, and so on and so forth, so I only end up running the last file. So, basically, I would like a way of reading the mp3 file length so that I can use 'time.sleep(SongLength)' between the start of each file.
Thanks in advance.
EDIT:
I forgot to mention, but I would prefer to do this using only pre-installed libraries, as i am hoping to publish this online as a part of a (much) larger program
i've managed to do this Using an external module, as after ages of trying to do it without any, i gave up and used tinytag, as it is easy to install and use.
Nothing you can do without external libraries, as far as I know. Try using pymad.
Use it like this:
import mad
SongFile = mad.MadFile("something.mp3")
SongLength = SongFile.total_time()