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<div name="messageBodySection" style="font-size: 14px; font-family: -apple-system, BlinkMacSystemFont, sans-serif;">Hi Steve,
<div><br /></div>
<div>I know what you mean. We already have a shortest path and I need to convert it to natural language and guide the driver on how to drive to the destination.</div>
<div><br /></div>
<div>We can determine how to guide the driver by comparing the directions of the two roads.<br /></div>
<div><br /></div>
<div>For instance，</div>
<div><br /></div>
<div>V1-Point 1 to point 2 vector</div>
<div>V2-Point 2 to point 3 vector</div>
<div><br /></div>
<div>Compare V1 and V2 , we can guide the driver how to do .</div>
<div>Based on the angle of the vector, we can determine the direction of rotation and the magnitude of the rotation. Or you don't need to turn to move forward, which requires us to perfect this standard.<br /></div>
<div><br /></div>
<div>For example, when the angle of rotation is less than 15 degrees, we can see it straight.<br /></div>
</div>
<div name="messageSignatureSection" style="font-size: 14px; font-family: -apple-system, BlinkMacSystemFont, sans-serif;"><br />
<div class="matchFont">Guanzhong Liu</div>
</div>
<div name="messageReplySection" style="font-size: 14px; font-family: -apple-system, BlinkMacSystemFont, sans-serif;">在 2019年2月19日 +0800 AM1:11，Stephen Woodbridge <stephenwoodbridge37@gmail.com>，写道：<br />
<blockquote type="cite" style="margin: 5px 5px; padding-left: 10px; border-left: thin solid #1abc9c;">Hi Guanzhong,<br />
<br />
I think your need to find the current pgrouting workshop (a tutorial)<br />
and work your way through it. What you describe is already possible<br />
because of the integration with postGIS and postgresql. For example you<br />
can select your edges for building a graph like:<br />
<br />
-- in pseudo-sql<br />
select * from edge_table<br />
where geom && st_expand(start, radius)<br />
or geom && st_expand(end, radius)<br />
or geom && st_make_line(start, end);<br />
<br />
But this has nothing to do with driving directions. Driving directions<br />
assumes you already have the shortest path and you neeed to turn that<br />
into maneuvers and then into natural language.<br />
<br />
-Steve<br />
<br />
On 2/18/2019 1:52 AM, 刘冠中 wrote:<br />
<blockquote type="cite" style="margin: 5px 5px; padding-left: 10px; border-left: thin solid #e67e22;">Hello Steve,<br />
<br />
Very happy to receive your letter.<br />
<br />
This is some of my ideas.<br />
<br />
We need a search range to find a path planning solution.I have three<br />
ideas：<br />
<br />
1.Build a rectangle from the start point to the end point.<br />
2.Build an ellipse from the start point to the end point<br />
3.Combine the two to find their common area<br />
/*Concept map in the attachment*/<br />
<br />
And I have two questions：<br />
<br />
1.Is there a grade distinction between roads, and whether<br />
stratification can improve efficiency?<br />
2.The limits of each road should also be considered. Can we get<br />
relevant information?<br />
<br />
<br />
<br />
Guanzhong Liu<br />
在 2019年2月16日 +0800 PM10:51，Stephen Woodbridge<br />
<stephenwoodbridge37@gmail.com>，写道：<br />
<blockquote type="cite" style="margin: 5px 5px; padding-left: 10px; border-left: thin solid #3498db;">Hello Guanzhong,<br />
<br />
Here is an outline for Driving Directions that I wrote up a few years<br />
ago.<br />
<br />
https://github.com/pgRouting/pgrouting/wiki/Driving-Direction-Instructions<br />
<br />
It discusses an approach to the problem and identifies some of the issue<br />
that need to be overcome or worked around. One thing you might want to<br />
do is to take a small data set like your city and get that working in<br />
pgrouting, then following the outline above try to get some of the steps<br />
working with that data. You can prototype this up in plpgsql stored<br />
procedures. My original implementation was done in plpgsql which was<br />
very fast and adequate for the task.<br />
<br />
I would break this down into two major task:<br />
1. the algorithms for generating the maneuvers and explicating the<br />
directions<br />
2. working out the details of how to make the solution generic<br />
<br />
Step 1. sets many of the requirements for step 2, like what is the<br />
minimum data needed for the analysis because this then needs to be<br />
configured in the generic solution, etc.<br />
<br />
I think this would be a very valuable contribution to pgrouting.<br />
<br />
Best regards,<br />
-Steve<br />
<br />
On 2/16/2019 6:32 AM, 刘冠中 wrote:<br />
<blockquote type="cite" style="margin: 5px 5px; padding-left: 10px; border-left: thin solid #d35400;"><br />
Hello，<br />
<br />
<br />
I am a senior at Beijing Institute of Technology in China. My major at<br />
university is computer science and technology. And Coding also is my<br />
hobby. Path planning is a topic I attended in the lab. I am very<br />
interested in your thoughts on "Implement generic driving directions<br />
add-on to pgRouting”.<br />
<br />
<br />
Thank you for reading and look forward to your reply.<br />
<br />
<br />
Guanzhong Liu<br />
<br />
<br />
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