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osrf / car_demo

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Questions about road width and the scale of the car #29

Open txzhao opened 6 years ago

txzhao commented 6 years ago

Hi,

Thanks for sharing your code. It's really an amazing work. I now have two questions about the model of car and world:

The first one is about the scale of the car. Looked at from the simulation, the car seems to be much smaller than what we expect in real-world cases when compared to the road. When I tried to check the width of the road (used as a reference), I couldn't find it in the code. So, could you give me some hints on where to find the width of the road?

Besides, when I checked the prius.urdf file, I noticed that the scale factor of chassis and wheels is "0.01 0.01 0.01". Does this mean that the unit in solidworks file is centimeter instead of millimeter? I would appreciate it if you could clarify this since I may need the right dimension for further modeling. Thanks in advance.

Cheers/Tianxiao

iche033 commented 6 years ago

We hired a 3D modeling artist to create these models. I have a feeling that the scale of the prius car model is correct. He worked in millimeters for this particular model and we scaled it to meters, hence the mesh has a scale of 0.01.

For the MCity model. It looks like, we're trying to convert from inches to meters but off by a factor of 0.1. Scale currently is 0.254 which seems odd. I would have expected 0.0254. So I think the scale of this model may be incorrect and we need to figure out what unit it's created in.

txzhao commented 6 years ago

Thanks for your quick reply! So if the scale of the car 0.01 is correct, does it mean that its size is kind of scaled up by a factor 10 since conversion from millimeters to meters should give out a scale of 0.001?

BTW, I just checked the coordinates of the car by driving the car to both sides of the road and then accessing the topic /bask_pose_ground_truth, and it turned out that the width of the road was around 14. So another two questions (sorry about so many lengthy questions): Is the unit of this absolute distance between two coordinates also meter? And is it scaled by 0.1 or not?

iche033 commented 6 years ago

So if the scale of the car 0.01 is correct, does it mean that its size is kind of scaled up by a factor 10 since conversion from millimeters to meters should give out a scale of 0.001?

oops, then he probably worked in centimeters

I'll look in to what unit the mcity model is created in

tfoote commented 6 years ago

Having setup the tf frames for the car, I believe it's scale is approximately correct.

menson168 commented 6 years ago

It seems like no fix has been done on it yet. Do you guys plan to have a fix implemented soon?

tfoote commented 6 years ago

This is a demo that runs, we're not actively work on it. If you want to test it with an updated scale and open a PR against it we'll try to find time to review it.

anantagrg commented 3 years ago

Is it possible to get the wheelbase of the vehicle and also the reference point on the vehicle, you are publishing odometry data to base_pose_ground_truth topic?