Re: [mapserver-users] converting line object to series of points
Thanks for your insights and help. The lines I'm working with will have multiple points. They are hurricane tracks. The tracks are made of points, about 3-12 hours apart. Therefore, sometimes the points are close and other times very far away from each other. I can easily connect the track points to create a line. But I need the points in between each observation so that I can determine what county landfall occurs. The y=mx+b method will work, but I was hoping there may be an easier to do it. Or perhaps I'm making the problem too complicated to begin with?? Mark Bob Basques wrote: All, If you don't care about the actual coordinates of the points along the line (just trying to display things) I wonder if a linetype/combined with a scaling option would get you what you are looking for. bobb >>> Andy Colson wrote: On 4/15/2010 10:51 AM, Mark Brooks wrote: > I'm using PHP Mapscript. I need a point every X meters along the line. > > Mark > > > Andy Colson wrote: >> On 4/15/2010 10:24 AM, Mark Brooks wrote: >>> I have a line object that I need to to turn into points. How can I >>> create a series of points from the line object? >>> >>> Mark >>> NC State University >> >> A line has many many points. Which are you interested in? Just the >> first and last? Any one point on the line? The mid-point? A point >> every meter along the line? The closes point on the line to some other >> object? >> >> I know of two options: >> 1) use PostGIS: >> select st_centroid(the_geom) from layer >> >> 2) use mapscript >> >> >> -Andy > Does the line have a single start and end point? (a MULTILINE record can have multiple lines (so multiple start and end points, all stuck togethor). In general, find the start and end points, use them to find the equation of the line (y=mx+b if I recall correctly), then use that equation to find one corrd based on another. (so, plug in a buch of x's to find their y's). -Andy ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] converting line object to series of points
I'm using PHP Mapscript. I need a point every X meters along the line. Mark Andy Colson wrote: On 4/15/2010 10:24 AM, Mark Brooks wrote: I have a line object that I need to to turn into points. How can I create a series of points from the line object? Mark NC State University A line has many many points. Which are you interested in? Just the first and last? Any one point on the line? The mid-point? A point every meter along the line? The closes point on the line to some other object? I know of two options: 1) use PostGIS: select st_centroid(the_geom) from layer 2) use mapscript -Andy ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
[mapserver-users] converting line object to series of points
I have a line object that I need to to turn into points. How can I create a series of points from the line object? Mark NC State University ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
Re: [mapserver-users] distance between line and a given point usingmapscript
I got the looping through each result. However, all distances are
calculated to -1, which I know can't be right. In debugging, I'm also
echo'ing the shape index for each result, but it's always the same. Am I
constructing the layer correctly?
// create array of points from database query results.
for ($i=0; $row=mysql_fetch_assoc($result); $i++){
$points[$row['snum']][$i]['lat'] = $row['lat'];
$points[$row['snum']][$i]['lon'] = $row['lon'];
} // End loop through points
// create map object
$map = ms_newMapObj('wms.map');
// create new layer for hurricane tracks.
$my_layer = ms_newLayerObj($map);
// set some fields for this new layer
$my_layer->set("toleranceunits","miles");
$my_layer->set("tolerance","20");
// Create new class and add TEMPLATE.
$my_class = ms_newClassObj($my_layer);
$my_class->set("template",'query_template.html');
// Loop through points, create line for each storm, and add track points
to new line object.
while (list($snum,$coordinates)=each($points)){
// Create new line object
$my_line = ms_newLineObj();
// Loop through each point coordinate for this snum
while (list($num,$coordinate)=each($coordinates)){
// Create new point object
$my_point = ms_newpointObj();
$my_point->setXY($coordinate['lon'],$coordinate['lat']);
// Add point to line object
$my_line->add($my_point);
} // done adding this storm's points to the line object
// Now create a new shape object
$my_shape = ms_newShapeObj(MS_SHAPE_LINE);
$my_shape->add($my_line);
// Add feature to the layer
$my_layer->addFeature($my_shape);
} // end creating and adding points to line objects and line objects to
the layer.
// Draw map.
$map->draw();
// Make a new point object that will be our reference point.
$my_ref_point = ms_newpointObj();
$my_ref_point->setXY(-78.7,35.4); // user-entered coordinates of where we
are querying from.
// Run a point query on the line object layer.
if (@$my_layer->queryByPoint($my_point,MS_MULTIPLE,-1)==MS_SUCCESS){
// Loop through results.
$num_results = $my_layer->getNumResults();
echo "# results = $num_results\n\n";
// Loop through each result
for ($num=0; $num<$num_results; $num++){
echo "result # $num:\n";
// Get this result
$my_result = $my_layer->getResult($num);
//$my_shape =
$my_layer->getShape($my_result->tileindex,$my_result->shapeindex);
// Get the shape
echo "shapeindex = ".$my_result->shapeindex."\n";
$my_shape = $my_layer->getFeature($my_result->shapeindex);
// Get the feature
echo "distanceToShape =
".$my_ref_point->distanceToShape($my_shape)."\n\n"; //
calculate distance from ref point to feature
}
}
On Mon, July 27, 2009 11:54 pm, Steve Lime wrote:
> There are lots of samples that show you how to loop through a set of
> search
> results. There's a getNumResults() method for layer objects and then a
> getResult()
> method to retrieve each one individually.
>
> Steve
>
>>>> Mark Brooks 07/27/09 9:50 AM >>>
> Steve,
>
> This is a huge help. The only thing I had not figured out was the
> 'toleranceunits' and 'tolerance' fields. I appreciate your help!
>
> I intend to add many, possible hundreds, lines to a layer. Then query
> it with a given reference point. How do I get the number of results and
> then loop through each one?
>
> Best Regards,
> Mark
>
>
> Steve Lime wrote:
>>> How do I query a layer with one or more line features to find all
>>> features with X miles of a given point?
>>
>> Your line layer should like so:
>>
>> LAYER
>> NAME 'lines'
>> TYPE LINE
>> ...other junk...
>> TEMPLATE 'dummy' # to be queryable
>> TOLERANCEUNITS MILES
>> TOLERANCE X
>> END
>>
>> Then in mapscript you'd do a
>>
>> $my_layer->queryByPoint($my_point, MS_MULTIPLE, -1);
>>
>> The buffer parameter is used to override a layer tolerance so setting to
>> -1 tells
>> the method to ignore it. If you do use it then it's given in the units
>> of the layer
>> being searched (before any projection).
>>
>> Does that help?
>>
>> Steve
>>
>>>>> Mark Brooks 07/24/09 3:26 PM >>>
>> I&#
Re: [mapserver-users] distance between line and a given point usingmapscript
Steve,
This is a huge help. The only thing I had not figured out was the
'toleranceunits' and 'tolerance' fields. I appreciate your help!
I intend to add many, possible hundreds, lines to a layer. Then query
it with a given reference point. How do I get the number of results and
then loop through each one?
Best Regards,
Mark
Steve Lime wrote:
How do I query a layer with one or more line features to find all
features with X miles of a given point?
Your line layer should like so:
LAYER
NAME 'lines'
TYPE LINE
...other junk...
TEMPLATE 'dummy' # to be queryable
TOLERANCEUNITS MILES
TOLERANCE X
END
Then in mapscript you'd do a
$my_layer->queryByPoint($my_point, MS_MULTIPLE, -1);
The buffer parameter is used to override a layer tolerance so setting to -1
tells
the method to ignore it. If you do use it then it's given in the units of the
layer
being searched (before any projection).
Does that help?
Steve
Mark Brooks 07/24/09 3:26 PM >>>
I'm trying to create several new line objects and then find the lines
that are within x miles of a given point. (i.e., how far away a given
point is from the track of a hurricane or the path of a ship). I'm
having some difficulties and I hope someone can help.
How do I query a layer with one or more line features to find all
features with X miles of a given point?
Here is how I'm approaching the problem in PHP:
// Test array of points. This is used to make a line.
$points[0]['lat'] = 35.5;
$points[0]['lon'] = -78.8;
$points[1]['lat'] = 36.5;
$points[1]['lon'] = -79.8;
$points[2]['lat'] = 37.5;
$points[2]['lon'] = -80.1;
// make new map object.
$map = ms_newMapObj('mapdata/mymap.map');
// Create new line
$my_line = ms_newLineObj();
// Loop through points, and add to the line
while (list(,$coordinate)=each($points)){
// Create new point object
$my_point = ms_newpointObj();
$my_point->setXY($coordinate['lon'],$coordinate['lat']);
// Add point to line object
$my_line->add($my_point);
}
// Now create a new shape
$my_shape = ms_newShapeObj(MS_SHAPE_LINE);
$my_shape->add($my_line);
// create new layer
$my_layer = ms_newLayerObj($map);
// set some fields for this new layer
//$my_layer->set("units","miles"); // does not seem to work as expected
// Create new class and add TEMPLATE. This is required for queries on
the layer to work?
$my_class = ms_newClassObj($my_layer);
$my_class->set("template",'/home/www/html/query_template.html');
// Add feature to the layer
$my_layer->addFeature($my_shape);
// Draw map. Query doesn't work if I don't do this now.
$map->draw();
// Make a new point object that will be our ref point
// to check how far away the line is from this point.
$my_point = ms_newpointObj();
$my_point->setXY(-82,36); // lon, lat
// Run a point query on the line object layer; layer must have a class
with a LAYER TEMPLATE value
// The third argument is the buffer tolerance. Default unit is pixels?
Must figure out how to make miles or km.
if ($my_layer->queryByPoint($my_point,MS_SINGLE,1)==MS_SUCCESS){
$my_result = $my_layer->getResult(0); // Get the result
$my_layer =
$my_layer->getShape($my_result->tileindex,$my_result->shapeindex); //
Get the shape
}
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--
Mark Brooks
State Climate Office of North Carolina
Box 7236, NC State University
Raleigh, NC 27695-7236
Phone: 919.515.1446
Fax: 919.515.1441
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[mapserver-users] distance between line and a given point using mapscript
I'm trying to create several new line objects and then find the lines
that are within x miles of a given point. (i.e., how far away a given
point is from the track of a hurricane or the path of a ship). I'm
having some difficulties and I hope someone can help.
How do I query a layer with one or more line features to find all
features with X miles of a given point?
Here is how I'm approaching the problem in PHP:
// Test array of points. This is used to make a line.
$points[0]['lat'] = 35.5;
$points[0]['lon'] = -78.8;
$points[1]['lat'] = 36.5;
$points[1]['lon'] = -79.8;
$points[2]['lat'] = 37.5;
$points[2]['lon'] = -80.1;
// make new map object.
$map = ms_newMapObj('mapdata/mymap.map');
// Create new line
$my_line = ms_newLineObj();
// Loop through points, and add to the line
while (list(,$coordinate)=each($points)){
// Create new point object
$my_point = ms_newpointObj();
$my_point->setXY($coordinate['lon'],$coordinate['lat']);
// Add point to line object
$my_line->add($my_point);
}
// Now create a new shape
$my_shape = ms_newShapeObj(MS_SHAPE_LINE);
$my_shape->add($my_line);
// create new layer
$my_layer = ms_newLayerObj($map);
// set some fields for this new layer
//$my_layer->set("units","miles"); // does not seem to work as expected
// Create new class and add TEMPLATE. This is required for queries on
the layer to work?
$my_class = ms_newClassObj($my_layer);
$my_class->set("template",'/home/www/html/query_template.html');
// Add feature to the layer
$my_layer->addFeature($my_shape);
// Draw map. Query doesn't work if I don't do this now.
$map->draw();
// Make a new point object that will be our ref point
// to check how far away the line is from this point.
$my_point = ms_newpointObj();
$my_point->setXY(-82,36); // lon, lat
// Run a point query on the line object layer; layer must have a class
with a LAYER TEMPLATE value
// The third argument is the buffer tolerance. Default unit is pixels?
Must figure out how to make miles or km.
if ($my_layer->queryByPoint($my_point,MS_SINGLE,1)==MS_SUCCESS){
$my_result = $my_layer->getResult(0); // Get the result
$my_layer =
$my_layer->getShape($my_result->tileindex,$my_result->shapeindex); //
Get the shape
}
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[mapserver-users] Re: shade a county
I figured it out. It was actually pretty easy. For reference to others
who might need to do this also, I'll post my methodology. I also have
one outstanding question at the end...
Mapscript snippet looks like this:
// Make a new point object
$cnty_layer = $map->getLayerByName('cnty');
$my_point = ms_newpointObj();
$my_point->setXY($lon,$lat);
// Run a point query on the county layer.
// layer must have a class with a LAYER TEMPLATE value
if ($cnty_layer->queryByPoint($my_point,MS_SINGLE,1)==MS_SUCCESS){
$cnty_result = $cnty_layer->getResult(0); // Get the result
$cnty_layer->open();// Open layer for use with getShape()
$cnty_shape=$cnty_layer->getShape($cnty_result->tileindex,$cnty_result->shapeindex);
// Draw the shape onto the shaded county layer
$cnty_shade = $map->getLayerByName('shade_red');
$cnty_shape->draw($map, $cnty_shade, $image);
}
Mapfile snippet that goes along with the above looks like this:
LAYER
NAME shade_red
TYPE POLYGON
STATUS ON
TRANSPARENCY 50 # use OPACITY in mapserver v5
CLASS
NAME "Red County"
COLOR 187 0 0
END
END
Notice the transparency in the layer above. I'm still on mapserver 4.x.
The problem is that the layer doesn't draw with any transparency, no
matter what I put as the value. Any ideas?
Mark
Mark Brooks wrote:
I have a shapefile of type polygon of all counties in the United States.
Given a latitude/longitude point, I want to shade/hatch the county that
it's in. I'm not sure of the best way to do this. Any suggestions?
I'm working with PHP Mapscript by the way.
Mark
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[mapserver-users] shade a county
I have a shapefile of type polygon of all counties in the United States. Given a latitude/longitude point, I want to shade/hatch the county that it's in. I'm not sure of the best way to do this. Any suggestions? I'm working with PHP Mapscript by the way. Mark ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
[mapserver-users] satellite / aerial imagery
I am working on a mapserver project and need satellite or aerial imagery, preferably at a very high resolution. Kind of like google maps satellite view. I assume raster or geotif would be the ideal file type. I only need imagery for North America. Can anyone suggest a good, hopefully free, resource for this? Much thanks, Mark NC State University ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
[mapserver-users] find max value in mapfile?
We have a shapefile of type 'point'. Is there a way to find the maximum value of all points in this shapefile? It would be cool to be able to do this in the mapfile. We're using PHP mapscript and want to create a dynamic color ramp based on the max/min values of the shapefile. Mark ___ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
