 So in this video, I want to have a look at how you can check your solution if it makes sense by using external reference like Google Maps for example So for that I open up a new shot and this is in camera tracking and then in Turin This has been filmed by some very nice members of the Italian Blender community from Turin and This should be very easy to track. So I will not explain anything I will just show you the time-lapse Where I put the markers and stuff, but other than that it should be totally easy to track that But since this is an open place in Turin You might want to be able to check if everything makes sense and for that you can use external reference So in the meantime, I have tracked the scene and I have to admit it was a little bit tedious because This thing right here went always in the way. So I had to make sure that these markers did not slide So I had to sometimes disable them manually. So that was a little bit tedious and time-consuming and Well, but other than that was pretty nice to track Of course next step is to try to solve that. So let's set these camera data Now I know that this shot has been recorded with a Canon 5D and Also that the lens has been 17 millimeter lens and that has also been noted here right there in the file name so we can just go ahead and set this to the Canon 5D and Then make sure that the focal length is set to 17 millimeters like that Let's first try with the default settings here But I somehow doubt that this will give the best results because a 17 millimeter lens will most likely have some lens distortion Okay, so we've got 1.4 ever at solve error, which is not that good So this really doesn't look right. So that is our camera curve the error per frame Enable all the markers then we can first check if everything's all right. So it looks quite okay There are no really bad spikes. Oh Maybe this one. I think that might be a bit dangerous. So what's happening here? Um, so there. Oh, that's this one. Okay, so that is a little jump and we can correct that cross only this one like so By the way, that is a very typical shape. So when you have something like that where you have this shape this This up and down then you know that you can just put the marker back on place and on the next frame It will be okay again. So that is always something that you can very easily correct but if the marker would have jumped away and then on this frame Continue to track that Then you have a very different shape So then you have this one jump and after that it will be flat again So you don't have this up and down but just up and then on the same level So that is something where you can or where you have to Correct everything that comes after that, but if it's really just up and down So then in the path you have this spike, but in the curve view you will have this up down up So that is very easy to correct G. Put it back on place. Now. We also have this smooth curve here But well other than that it looks okay. So everything is pretty smooth. So in theory, we should get a much better value here So of course we have to correct something and first of all we can try if we can improve that by choosing different keyframes So let's see. We have on frame one It's here then on frame 30 It looks like that, but I must say that this should be really enough to establish the perspective So I think that the keyframes are all right. We might Try to set it to something I don't know maybe here So 250 and 290 But still we get the same value here. So maybe we can try to enable the refinement Shift s And well that didn't really help. So for some reason blender has not been able to trigger the refinement So in that case we now have to try to find out the distortion values manually So we go to tracking and then set this to the distortion mode Then we can also hide the curves. So press z And now we should try to find some straight lines, which in this case is very easy So we go to grease pencil and either we click here and then create a straight line Or we do that with shortcut by holding down the d key and the control key Then left click here Keep the mouse pressed and now we can Place this line over here Maybe a little bit more accurate. So let me try again from here to there. All right Then also this of course should be a straight line, but I can already see that this is kind of curved So d control click here Move that down there and you can see that the line is not really lining up with the line that we see here So the footage is kind of bent. So it's not as straight as it should be Of course, you never know if the lines in the footage are really 100 straight But in this case chances are that these lines are really straight lines Okay, like that and now we can try to manually Set the lens distortion. So first of all, let's Put this to some negative value So draw the k1 slightly into the negative direction And when you are in distortion mode Then here in display you have automatically the manual calibration enabled So you will see the effect of this manual lens distortion calibration in the grease pencil So when you draw this to the negative direction, then this lines up a little bit better now Also here that looks better But just from experience, I know that when I drag the k1 value into the negative direction Then if I would be able to use the automatic calibration for k2 Then the k2 value would be something in the positive direction And by using that I will drag this back. So that this is now bent again So I have to work against that with the k1 value And here like that I can start to adjust that so that this fits Okay, let's try again Tap key to go back to tracking mode And I keep the refinement enabled and eventually The manual calibration can now help us to trigger the automatic refinement So shift s to solve And that looks very promising. So if refining takes a little bit longer Then it really tries to calculate something and now look at that. We are at 0.5, which is perfect We also see that the focal length is still at 17 and that our manual calibration here was not too bad So changing these values has now been able to trigger the refinement. So that should now be a pretty great solution So let's have a look at that in 3d view. Maybe before we can just get rid of that grease pencil like that and then Again divide that go to 3d view Then scroll down here to get to the clip settings Then enable setup tracking scene and before we continue, of course, we have to set the floor So for the orientation, we pick some markers that are on the floor, of course And in that case, I want to use something here because that is not flat on the ground that goes up a little bit So for that, I will use this one this one and maybe that one Then tap to go to the reconstruction mode set floor Then also we can already set some origin So maybe this one could be our origin Like that and because this is nicely in line I pick this one and then set this as y-axis But if I press 7 to look from above then I would rather have that in the opposite direction So I click on y-axis again so that the camera is now here And we've got these markers now here indicating where our buildings are All right, like that then end to be able to go to the motion tracking panel So that we can make the size a little bit bigger Also, maybe let's set a scale so Let's see the typical Height of of a door is maybe two meters So I can pick these and then say set scale is two meters the distance of these Like that Okay, so let's start inserting some geometry so maybe Fullscreen then control odd q for the quad view Then I want to adjust that so that this now sits on the floor Then also maybe use this plane to try to line that up So let's see in the first frame I need the timeline here Okay, maybe here This should be lining up To that line And of course, let's not forget to also enable the proxy Just so that the camera view is able to use the render undistorted feature So enable the checkbox here proxy timecode And then in the 3d view You can see that automatically The background images are now able to use this setting render undistorted So now we have straight lines in the footage and that will of course fit much better to the geometry here So that looks good Then scale that up along the y-axis So that could be better, but I think it's still okay Maybe we can even rotate this just a little bit So now that lines up nicely Like so Then in wireframe could also try to Line that up here like that Yeah, that looks fine And now if I want to match that to To this line Then I know that these are probably in line these blocks So if I look at that This one These should be I mean Or should they I don't know Maybe they should at least I would think that they are In a rectangle to This line But if I now insert a plane here To match these then That really doesn't fit at all I mean, it's not terribly bad, but this is definitely not a line So well first of all this of course goes not flat, but this is slightly uphill I don't know the correct word for that So right here at our origin I will First of all make sure that The origin is here by first centering the cursor there then origin set cursor. So now I can press r and then y To rotate that Also Should be here like that Yes, r y a little bit more Like so Then e to extrude And well, it doesn't really line up that nicely So that doesn't really fit So something seems to be wrong and now well, I mean we could of course try to Fix our curves or get a new solution But Well, it would be just easier to know exactly if that makes sense or not If you could somehow find out if this is really exactly that what it should be And in that case it really helps to use a map for reference So if you know where this has been shot, then just use a map or go to google maps and look it up. So Eventually, this is just not straight line, but maybe this is in fact just not rectangular So in our example, I know that this has been recorded in Turin. So of course we can just look it up Turin In Italy, so that is here And then let's have a look if you can find this place So here we've got the city And then we should look for a place Seems to be the center of town So there are some places here Maybe let's zoom in a little bit more And that already looks familiar here. So if I zoom in a little bit more, then That is the place So here you can see we have these Curved lines of this building that you can also see here So that is this then we've got these lines on the floor And in fact they are not straight. So we've got here our lines. The camera would be somewhere around here And well, that is not rectangular. That is a little bit different here So these are our markers that we have here So here here here and here we've got place our markers. So in fact our solution is kind of okay And maybe we can really find out if it is really correct By taking a screenshot and bringing that into Blender So I will just use my screen grab tool That is in this case the one from os 10 So I've taken this screen capture and then I go back to Blender Now, of course, I could just use the background images But because the image in google maps has been rotated slightly I rather want to use an empty for that So shift a and then add an empty And here in the empties properties You can go to the display options and set it to display an image Like that then just click on open and navigate to the folder with your screen grab and import that Like so and of course I want to scale it up a little bit So s and then scale Something like that then also let me just bring that down here so that it is slightly below our markers Then seven to look from the top like that maybe lower the transparency a little bit And now we can try to line that up So first let's line up the origin of our scene On this block that one right here with a block in the footage So we have to scale it and then I think that this might be this block So let's press g and then bring that here to the origin of the scene Like so maybe And then also press shift c to make the cursor go to the center of the scene Then make sure that the pivot point is also set to 3d cursor Like that so that we can now press r and then not rotate around the origin of the object But around the origin of the scene or around the 3d cursor So r to rotate that until it is lining up more or less Like that and now we can start scaling so that These points in the corner are here where I suspect that the actual points might be Now s to scale it up until these points are on this corner more or less something like that And now you can see that here our points that we have Marked here these tracks are in fact at the correct positions And also they are in line with this line from this image here And even the points that we have marked on the roof of the of this building here Maybe not exactly but more or less they are In fact lining up so at least we know that this line is Correct And then of course with that information. It's very easy to just put in everything you want in your scene So it's a really good idea to get some reference So whenever you're shooting outside Then you can just use google earth or google maps or just regular maps and use that as a reference Or if you're shooting indoors, then maybe you just want to measure the whole set so that you exactly know What the dimensions are if lines are straight or how Big they are or you know, whatever your set might look like So if you know the exact dimensions and the exact appearance of your set Then it will be much easier for you to really know if your solution is correct And then to implement this stuff in that or maybe you also realize that some lines are just not For example rectangular where they should be So then you might have to go back and have a look at your solution and maybe adjust something So having a reference is always a good idea