1 00:00:01,320 --> 00:00:05,800 Throughout this course, we have been organizing our code within a Roth package. 2 00:00:05,820 --> 00:00:11,190 In this lecture, we're going to take a look at Rust, two packages made by other developers and use 3 00:00:11,190 --> 00:00:11,460 it. 4 00:00:11,940 --> 00:00:16,290 The packages we will ultimately be using is the USB cam package. 5 00:00:16,290 --> 00:00:18,000 You should be able to follow along with me. 6 00:00:18,000 --> 00:00:23,690 If you have a laptop with a built in camera or a camera which you can plug in via USB. 7 00:00:24,570 --> 00:00:26,340 First thing to do before we get into anything. 8 00:00:26,340 --> 00:00:30,540 Ross related is a check that our camera works properly in Ubuntu. 9 00:00:30,570 --> 00:00:34,770 We can use an app called cheese, which should be installed by default. 10 00:00:34,830 --> 00:00:38,940 If I click on it, you can see a window open which shows my camera feed. 11 00:00:39,990 --> 00:00:40,560 Hello. 12 00:00:43,350 --> 00:00:47,430 If you're unable to get that to work, chances are you will also have a hard time trying to get it to 13 00:00:47,430 --> 00:00:47,820 work in. 14 00:00:47,820 --> 00:00:48,570 Ross. 15 00:00:48,780 --> 00:00:54,210 If you are using a virtual machine, make sure to configure your virtual machine settings USB to be 16 00:00:54,210 --> 00:00:59,070 able to utilize USB three ports if that is what your camera is plugged into. 17 00:01:00,810 --> 00:01:03,860 With that out of the way, let's get to the rock packages. 18 00:01:03,870 --> 00:01:08,550 Let's go ahead and open up a browser to search for readily available rescue packages. 19 00:01:08,550 --> 00:01:11,100 We can check out the Ross Index site. 20 00:01:11,490 --> 00:01:17,430 If you have used Ross one before, you are probably more familiar with the Ross wiki to find information 21 00:01:17,430 --> 00:01:18,930 about packages. 22 00:01:18,930 --> 00:01:25,020 Justin Keep in mind that going forward all Ross to package info will instead be found on the Ross index 23 00:01:25,020 --> 00:01:27,900 page and will not be kept on this Ross wiki. 24 00:01:28,410 --> 00:01:29,550 On the Ross Index home page. 25 00:01:29,550 --> 00:01:33,210 You can see the current active distributions at the time of this recording. 26 00:01:33,210 --> 00:01:40,710 You may see different distros as galactic will be depreciated in November 2022 and melodic in May 2023. 27 00:01:41,010 --> 00:01:44,820 If you click on any of these links, it'll take you to the general distribution Description page. 28 00:01:45,210 --> 00:01:50,610 Instead, we are interested in checking out some of the Ross packages available so I can hit the packages 29 00:01:50,610 --> 00:01:52,530 list button in the upper left. 30 00:01:53,170 --> 00:01:58,840 Here we get a list of Ross packages for the humble distribution sorted by latest release date. 31 00:01:58,870 --> 00:02:03,490 You could click on other distributions to check out the corresponding supported packages. 32 00:02:03,800 --> 00:02:08,740 Package we are going to be using is called USB cam so I can go ahead and search for it in the search 33 00:02:08,740 --> 00:02:09,220 bar. 34 00:02:10,270 --> 00:02:11,290 We get some results. 35 00:02:11,290 --> 00:02:15,820 And near the top we see the USB cam package for the humble distribution. 36 00:02:15,820 --> 00:02:17,380 So I'll go ahead and click on that. 37 00:02:18,370 --> 00:02:20,590 So here we're taking to the package page. 38 00:02:20,740 --> 00:02:24,040 At the top you can see the supported distros for this package. 39 00:02:24,800 --> 00:02:25,850 And slightly lower. 40 00:02:25,850 --> 00:02:31,160 We can see things such as the package description, summary and repository information. 41 00:02:31,280 --> 00:02:37,520 If we scroll down further, we'll get brought to a redmi MD file in the package repo, which generally 42 00:02:37,520 --> 00:02:41,990 gives a detailed description of what the package is and how to use it. 43 00:02:43,320 --> 00:02:48,210 And past that we get a changelog with various changes that were made to this package. 44 00:02:48,210 --> 00:02:49,830 So I'll go ahead and scroll back up. 45 00:02:50,970 --> 00:02:57,150 So here in the redmi it tells us how to install the package with apt install as well as instructions 46 00:02:57,150 --> 00:02:59,100 on how to build a package from source. 47 00:02:59,100 --> 00:03:01,140 And we can scroll down further. 48 00:03:02,380 --> 00:03:08,170 To see examples of running this node using the available launch files and nodes. 49 00:03:08,440 --> 00:03:11,950 And one last thing I want to show before we get into this is near the top. 50 00:03:11,950 --> 00:03:15,130 You can find a link to the repository which the package is hosted on. 51 00:03:15,130 --> 00:03:19,510 So here if we head over to browse code, I can go ahead and open this in a new tab and which takes us 52 00:03:19,510 --> 00:03:26,410 to, in this case, a GitHub page which hosts the code development for this USB cam package. 53 00:03:26,410 --> 00:03:30,700 So if you ever want to look at the source code before installing a package, this is one of the ways 54 00:03:30,700 --> 00:03:31,810 you could go about doing it. 55 00:03:31,810 --> 00:03:33,580 So for example, we can check out the launch files. 56 00:03:33,580 --> 00:03:36,340 So here we see there's a demo launch py file. 57 00:03:37,320 --> 00:03:41,940 And we can see some of the scripts that are available, such as Show Image Pie. 58 00:03:42,150 --> 00:03:43,740 So I'll go ahead and close that. 59 00:03:44,500 --> 00:03:44,770 All right. 60 00:03:44,770 --> 00:03:49,690 With that intro out of the way, let's go ahead and install this package so we can use our USB camera 61 00:03:49,690 --> 00:03:50,780 with Ross. 62 00:03:50,800 --> 00:03:56,320 So here in the Quickstart section I mentioned earlier, we can install this package using the apt install 63 00:03:56,320 --> 00:03:57,100 command. 64 00:03:57,550 --> 00:04:03,910 So it's simply apt install Ross followed by the distribution name and then the name of the package which 65 00:04:03,910 --> 00:04:06,100 is USB dash can. 66 00:04:07,040 --> 00:04:12,440 Worth mentioning that package names use an underscore snake case convention to separate words. 67 00:04:12,830 --> 00:04:19,850 So this package name is USB underscore cam, but note that the APT install command follows a dash convention 68 00:04:19,850 --> 00:04:23,920 in which each word is separated with a dash instead of an underscore. 69 00:04:23,930 --> 00:04:27,890 So auto students sometimes wonder why they can't install a package, and usually it's because they don't 70 00:04:27,890 --> 00:04:32,450 follow this particular command line convention when trying to run app install. 71 00:04:32,630 --> 00:04:35,390 But let's go ahead and open up a terminal and install it. 72 00:04:38,170 --> 00:04:41,110 So the way I have this command format, it works just fine. 73 00:04:41,110 --> 00:04:44,740 But note another popular convention you may see is the following. 74 00:04:47,600 --> 00:04:52,040 Now, this may seem weird and much more complex than what I had before, but this command will install 75 00:04:52,040 --> 00:04:58,040 the package regardless of what ros distro you have installed and source by utilizing the Ross distro 76 00:04:58,040 --> 00:05:01,090 environment variables so I can actually go ahead and open up a second terminal. 77 00:05:01,100 --> 00:05:03,440 And if I echo this environment variable. 78 00:05:05,840 --> 00:05:09,800 So echoing it, we see we get humble, which is the name of our Disher that we're using. 79 00:05:09,800 --> 00:05:15,710 So essentially in this command where we have this dollar sign Ross distro, this gets replaced with 80 00:05:15,710 --> 00:05:18,290 the string humble just as we saw earlier. 81 00:05:18,680 --> 00:05:23,990 But if we're using a different distribution such as Foxy or Noetic, then the above command will still 82 00:05:23,990 --> 00:05:26,830 install the correct distribution version of the package. 83 00:05:26,840 --> 00:05:32,060 So I'll go ahead and close the second terminal and go ahead and install the USB cam package. 84 00:05:33,230 --> 00:05:33,500 Go ahead. 85 00:05:33,500 --> 00:05:34,400 Put in your password. 86 00:05:36,190 --> 00:05:37,140 Or why? 87 00:05:37,140 --> 00:05:37,770 Enter. 88 00:05:40,400 --> 00:05:40,700 OC. 89 00:05:40,700 --> 00:05:43,020 We have installed the USB cam package. 90 00:05:43,040 --> 00:05:48,020 Packages installed this way can be found in your op ross distro folder. 91 00:05:50,310 --> 00:05:57,240 Some of the files, such as the launch and package files, will end up in the share folder and the executables 92 00:05:57,240 --> 00:06:03,390 can be found in the lib folder so I can head over to share and then we'll scroll to the bottom. 93 00:06:05,070 --> 00:06:06,780 And we can see USB cam. 94 00:06:06,900 --> 00:06:13,320 And here we can see some of the package files such as the launch folder and other environment and configuration 95 00:06:13,320 --> 00:06:14,010 files. 96 00:06:15,600 --> 00:06:16,590 If I go back. 97 00:06:17,450 --> 00:06:18,530 Can head over to lib. 98 00:06:19,590 --> 00:06:20,400 Scroll down. 99 00:06:22,200 --> 00:06:23,060 Yes, we can. 100 00:06:23,070 --> 00:06:27,270 And here we actually can see some of the nodes that were available in this package. 101 00:06:27,860 --> 00:06:32,900 So now that we have this package installed, let's go ahead and run the launch file we saw earlier. 102 00:06:35,220 --> 00:06:36,840 Since we installed it with app install. 103 00:06:36,840 --> 00:06:41,640 It is now part of our ROS Humble installation environment, so by default we can use the package without 104 00:06:41,640 --> 00:06:43,770 having to do any extra environment sourcing. 105 00:06:43,770 --> 00:06:47,730 So go ahead and clear the screen and then we can run it like so. 106 00:06:53,930 --> 00:06:59,180 If all goes well, you should see a pop up window displaying your image feed from your camera. 107 00:06:59,510 --> 00:07:00,170 Hello. 108 00:07:00,560 --> 00:07:05,120 You can also open a new terminal and see the various topics the USB cam node is publishing. 109 00:07:10,000 --> 00:07:14,950 Can then go ahead and stop the launch file by hitting control C in the particular terminal and you might 110 00:07:14,950 --> 00:07:15,820 get a crash report error. 111 00:07:15,820 --> 00:07:18,340 But that was just the UI of the show image. 112 00:07:18,340 --> 00:07:19,450 PY file closing. 113 00:07:20,680 --> 00:07:21,010 Great. 114 00:07:21,010 --> 00:07:24,520 So we successfully installed and use this Ross package. 115 00:07:24,550 --> 00:07:29,300 If you ever want to remove it, you can do so like any other app program using the app. 116 00:07:29,320 --> 00:07:30,220 Remove call. 117 00:07:33,590 --> 00:07:35,300 Go ahead and hit Y and enter. 118 00:07:37,560 --> 00:07:39,510 And now that package has been removed. 119 00:07:39,510 --> 00:07:44,040 So if I actually go back to our humble distribution, I could head over to share. 120 00:07:44,400 --> 00:07:49,290 And if I scroll down to the bottom, we now no longer have that USB camera directory. 121 00:07:50,060 --> 00:07:53,930 And just to confirm this further, you can go ahead and relaunch the demo launch pie. 122 00:07:53,930 --> 00:07:57,170 And of course, USB cam package is not found. 123 00:07:57,410 --> 00:08:01,840 Now, let's take a look at installing ROS packages by building them from source. 124 00:08:01,850 --> 00:08:04,910 So let's head back to the ROS index page. 125 00:08:04,910 --> 00:08:09,050 So again, you can head over to browse code and it'll take you to the source code location, which in 126 00:08:09,050 --> 00:08:10,540 this case is GitHub. 127 00:08:10,550 --> 00:08:16,190 So what I actually want to do is clone this repo, which is actually a ROS package, right? 128 00:08:16,190 --> 00:08:18,410 So just like what we've been creating so far. 129 00:08:18,410 --> 00:08:23,420 So if I go over to code, we can copy this URL. 130 00:08:23,780 --> 00:08:30,320 And now if I head over to our terminal and just to show you what's going on here, I'll go into workspaces 131 00:08:30,320 --> 00:08:32,510 Ros to my workspace and source. 132 00:08:32,510 --> 00:08:36,560 And again, this is the location of all the packages which are located in our workspace. 133 00:08:36,560 --> 00:08:42,260 So we're going to be putting the USB cam package here alongside our Udemy ROS two package. 134 00:08:42,260 --> 00:08:52,640 So I'll go ahead and resize this so we can see what's going on and I'll change into this directory. 135 00:08:52,640 --> 00:08:52,970 All right. 136 00:08:52,970 --> 00:08:58,970 So we see our ROS two package and now we're going to be using the Git Clone command to clone that USB 137 00:08:58,970 --> 00:09:00,050 cam repository. 138 00:09:04,830 --> 00:09:05,160 All right. 139 00:09:05,160 --> 00:09:10,830 So now we see this USB cam package has the folders and corresponding things related to what we're seeing 140 00:09:10,830 --> 00:09:12,840 here in the GitHub. 141 00:09:13,140 --> 00:09:17,520 Although if you notice, it actually looks a little bit different and that's because we're using the 142 00:09:17,520 --> 00:09:19,510 standard master branch. 143 00:09:19,530 --> 00:09:22,560 So GitHub repositories have branches. 144 00:09:22,560 --> 00:09:28,960 So here we can see a series of different branches which is develop Master Ros two and so on. 145 00:09:29,010 --> 00:09:35,070 So we want this Ros to branch, which is what got sent to us when we clicked on the ROS index page. 146 00:09:35,160 --> 00:09:39,030 So in order to switch branches, all we have to do is go into the folder. 147 00:09:40,620 --> 00:09:47,430 So again, we'll take a look at this and I'll close this just a little bit and then I can switch the 148 00:09:47,430 --> 00:09:52,830 branch using the git switch command called by the name of the branch, which in this case is ROS two. 149 00:09:53,010 --> 00:09:57,990 And here, if you were looking over here to the left, you saw that the file's changed because now we're 150 00:09:57,990 --> 00:10:01,440 using the corresponding branch of the files we're seeing here. 151 00:10:01,590 --> 00:10:04,260 So with that, I have the right code within this package. 152 00:10:04,260 --> 00:10:06,810 So now I just need to compile my workspace. 153 00:10:06,810 --> 00:10:09,180 So I'll go back into my workspace folder. 154 00:10:10,500 --> 00:10:11,460 And I'll run. 155 00:10:11,460 --> 00:10:12,450 Call can build. 156 00:10:13,980 --> 00:10:17,280 And of course, you can add your normal options, such as Simulink install. 157 00:10:19,860 --> 00:10:23,940 And here I will specify that I only want to rebuild the USB cam package. 158 00:10:23,940 --> 00:10:29,190 I don't want to have to rebuild our Udemy Ross two package so I can do this with the packages. 159 00:10:29,190 --> 00:10:30,300 Select flag. 160 00:10:33,570 --> 00:10:39,330 And then specify the only package I want to rebuild, which in this case is USB cam. 161 00:10:39,720 --> 00:10:41,190 So I'll go ahead and expand this a little bit. 162 00:10:41,190 --> 00:10:42,590 Just you can see the full command. 163 00:10:42,600 --> 00:10:46,920 So there we go, Colon build Simulink install package, select USB cam. 164 00:10:47,610 --> 00:10:48,900 So if I go ahead and hit enter. 165 00:10:54,940 --> 00:10:55,300 All right. 166 00:10:55,300 --> 00:10:59,380 So notice here we tried to build, but it seems we're missing something. 167 00:10:59,380 --> 00:11:02,320 It says no such file or directory fatal error. 168 00:11:02,320 --> 00:11:06,460 It tried to include this camera info manager http file. 169 00:11:06,460 --> 00:11:10,510 So for those of you who don't understand C++ debugging, that's fine. 170 00:11:10,510 --> 00:11:15,730 All that's really happening here is we are missing some core dependencies to our USB cam package. 171 00:11:15,730 --> 00:11:20,700 So notice throughout the course we've been updating our package on XML files. 172 00:11:20,710 --> 00:11:27,070 So if we open this with text editor, we see this has its own types of dependencies just like our package 173 00:11:27,070 --> 00:11:33,490 has, so we're most likely missing this camera info manager dependency, which this ROS package depends 174 00:11:33,490 --> 00:11:33,940 on. 175 00:11:34,330 --> 00:11:39,490 So the reason for this package of XML file is to tell us the dependencies we need and then we can actually 176 00:11:39,490 --> 00:11:42,700 install them automatically using the Ross DEP command. 177 00:11:50,260 --> 00:11:53,740 So here we're telling it to insult dependencies from source. 178 00:11:53,740 --> 00:11:54,850 So don't worry about this. 179 00:11:54,850 --> 00:11:56,140 Ignore source at the end. 180 00:11:56,140 --> 00:12:01,810 All this is saying is it ignores installing any dependencies if they are already exists within the workspace. 181 00:12:01,810 --> 00:12:03,040 So this is very helpful. 182 00:12:03,040 --> 00:12:08,830 If you had multiple different ROS modules which you wanted to freeze at a certain instance and instead 183 00:12:08,830 --> 00:12:13,960 of installing those dependencies directly onto your computer, it'll make sure to reference the ones 184 00:12:13,960 --> 00:12:15,430 in the workspace. 185 00:12:15,430 --> 00:12:18,040 But for now, let's just ignore that and we'll just go ahead and hit enter. 186 00:12:20,110 --> 00:12:20,950 I made a typo here. 187 00:12:20,950 --> 00:12:22,030 I meant to say source. 188 00:12:22,030 --> 00:12:28,210 So here we can see it's running apt install Ros humble camera and volt manager and we're going to have 189 00:12:28,210 --> 00:12:29,800 to put in our password for this. 190 00:12:29,970 --> 00:12:33,790 It's going to do this for all of the missing dependencies automatically for us. 191 00:12:39,720 --> 00:12:43,380 So here it says all required raw steps were installed successfully. 192 00:12:43,380 --> 00:12:48,480 So go ahead and clear the screen and now we can try and rebuild our workspace. 193 00:12:50,490 --> 00:12:54,770 So we'll be running our coal can build command and just rebuilding that USB cam package. 194 00:12:54,780 --> 00:12:56,370 So try running this one more time. 195 00:12:56,850 --> 00:13:00,840 And it seems we're still running into issues, so I'm going to go ahead and do is restart our workspace 196 00:13:00,840 --> 00:13:02,970 instance because it seems like something's bugged out. 197 00:13:02,970 --> 00:13:08,940 So I will be deleting our build, install and log folders so that we'll be recreating them when we run. 198 00:13:08,950 --> 00:13:09,900 Coal can build. 199 00:13:15,050 --> 00:13:17,240 Make sure not to delete the source folder. 200 00:13:18,680 --> 00:13:20,360 So now we only have our source folder. 201 00:13:22,110 --> 00:13:28,260 Here in our workspace and I'll rerun the can build command and we'll just build all packages in this 202 00:13:28,260 --> 00:13:28,950 case. 203 00:13:33,140 --> 00:13:34,040 And there we go. 204 00:13:34,040 --> 00:13:39,110 So I know that was a little bit of a rough patch there, but essentially sometimes when we're compiling 205 00:13:39,110 --> 00:13:43,790 things, it'll save certain sym links within our build file so that we can build faster the next time 206 00:13:43,790 --> 00:13:44,270 around. 207 00:13:44,270 --> 00:13:49,370 And it most likely saved something which made it continue to think that the camera info manager did 208 00:13:49,370 --> 00:13:50,450 not exist properly. 209 00:13:50,450 --> 00:13:56,780 So we just simply restarted our workspace by deleting the build, install and log folders and everything 210 00:13:56,780 --> 00:13:58,250 compiled successfully. 211 00:14:09,730 --> 00:14:12,160 So now let's go ahead and source this workspace. 212 00:14:17,140 --> 00:14:20,530 And try rerunning the demo launch file we ran earlier. 213 00:14:28,760 --> 00:14:29,330 Hello. 214 00:14:32,230 --> 00:14:37,060 Last but not least, to remove this package from your workspace, you'll need to delete the package 215 00:14:37,060 --> 00:14:38,290 from your source folder. 216 00:14:38,290 --> 00:14:44,770 So just go ahead and delete that and you will need to remove your build, install and log folders again, 217 00:14:44,770 --> 00:14:48,370 just as we did earlier, because there will still be instances pointed to it. 218 00:14:48,370 --> 00:14:53,890 So in this case we still have connections to this USB cam package which no longer exists. 219 00:14:53,890 --> 00:14:59,530 So we'll just go ahead and delete these one more time and rerun our. 220 00:15:03,710 --> 00:15:03,960 All right. 221 00:15:03,960 --> 00:15:08,660 And we got a little warning message because we are a source to our environment, which was deleted momentarily 222 00:15:08,660 --> 00:15:09,140 there. 223 00:15:09,320 --> 00:15:13,250 But you can see our roster package has finished compiling. 224 00:15:13,250 --> 00:15:18,200 So we're back to normal to the way we were with our workspace before this lecture started. 225 00:15:18,200 --> 00:15:22,790 In the future, I believe they will integrate a Coke and clean functionality similar to what Cat Can 226 00:15:22,790 --> 00:15:27,920 Clean did for Ross one, which is able to figure out which files belong to what packages and delete 227 00:15:27,920 --> 00:15:28,430 them for you. 228 00:15:28,430 --> 00:15:31,690 So you don't have to do this part manually like we just did. 229 00:15:31,700 --> 00:15:35,030 So I'll be on the lookout for that when that makes its way to official release. 230 00:15:36,660 --> 00:15:40,950 Now, why would you build from source if using app install is so much easier? 231 00:15:41,220 --> 00:15:47,640 Well, sometimes you may find community ROS packages which are not published to the ROS index or sometimes 232 00:15:47,640 --> 00:15:51,750 people want to freeze dependencies they are using within their own workspace. 233 00:15:51,760 --> 00:15:57,600 So it is important to know about how to build other people's packages from its source code, which we've 234 00:15:57,600 --> 00:16:02,250 been practicing throughout the previous section by compiling our own code within our workspace. 235 00:16:02,400 --> 00:16:07,980 But with that you have successfully learned how to install packages using app install and by building 236 00:16:07,980 --> 00:16:09,410 it within our workspace. 237 00:16:09,420 --> 00:16:15,360 This allowed us to download another ROS developer's package which has launch files and nodes that allow 238 00:16:15,360 --> 00:16:20,280 us to publish the image tree from our USB camera over ROS to.