If you only have a height above ground level for the starting point of a polygon: Is there a way to create the polygon so that all the following points have the same height relative to sea level? i.e. the polygon will be flat on the horizontal plain regardless of the terrain.
Does anyone have a method of doing this without knowing/obtaining the height above sea level before generating the kml?
Any help would be greatly appreciated.
Create a polygon using relativeToGround altitudeMode, which interprets the altitude as a value in meters above the ground.
Note: you'll need to specify the altitude value for each point. Can't just specify altitude for one and have others use same altitude. If you omit altitude it defaults to "0".
Here's polygon with each point set at 10 meters above ground.
<?xml version="1.0" encoding="utf-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
<Placemark>
<name>tennis-poly</name>
<Polygon>
<altitudeMode>relativeToGround</altitudeMode>
<outerBoundaryIs>
<LinearRing>
<coordinates>
-122.43193945401,37.801983684521,10
-122.431564131101,37.8020327731402,10
-122.431499536494,37.801715236748,10
-122.43187136387,37.8016634915437,10
-122.43193945401,37.801983684521,10
</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>
</kml>
If want the polygon to be flat on the horizontal plain regardless of the terrain then the altitudeMode must be absolute which is respect to mean sea level. You could skip defining the altitude in the coordinates and specify a single height using a <gx:altitudeOffset>.
<?xml version="1.0" encoding="utf-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2">
<Placemark>
<name>tennis-poly</name>
<Polygon>
<altitudeMode>absolute</altitudeMode>
<outerBoundaryIs>
<LinearRing>
<gx:altitudeOffset>50</gx:altitudeOffset>
<coordinates>
-122.43193945401,37.801983684521
-122.431564131101,37.8020327731402
-122.431499536494,37.801715236748
-122.43187136387,37.8016634915437
-122.43193945401,37.801983684521
</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>
</kml>
Your only possible woraround of this would be to get the sea level height of the first point and use that height on the other points as well:
Get altitude by longitude and latitude in Android
Related
I am attempting to generate a KML overlay. I have a grid I am mapping over an area, with colored squares. When I have the altitude mode as 'clampToGround' everything about the polygons I am generating, including their color, works as expected. However, it's not desirable to have the grid deform to map to the ground. When I change the altitude mode such that the overlay hovers a few meters off the ground, the shape of the grid sections is correct, but the color information is discarded and the grid sections are colored black.
Here is a testable excerpt of my KML code. Here is shows the colors correct but the grid deformed to the ground. Changing the value of altitudeMode to:
absolute produces the other behavior.
Is there a way to have this at the correct altitude AND with the correct color at the same time?
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2">
<Document id="1">
<Document id="2">
<Style id="10">
<PolyStyle id="10">
<color>0xFF0000FF</color>
<colorMode>normal</colorMode>
<fill>1</fill>
<outline>1</outline>
</PolyStyle>
</Style>
<name>Antenna Data</name>
<Camera>
<longitude>-122.30201334502573</longitude>
<latitude>37.87244901754293</latitude>
<altitude>200</altitude>
</Camera>
<Placemark id="5">
<name>region</name>
<styleUrl>#10</styleUrl>
<Polygon id="4">
<altitudeMode>clampToGround</altitudeMode>
<outerBoundaryIs>
<LinearRing id="8">
<coordinates>-122.30243999999999,37.871973499999996,10 -122.30243999999999,37.8719265,10 -122.30238,37.8719265,10 -122.30238,37.871973499999996,10</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>
</Document>
</Document>
</kml>
Your KML has several issues.
The polygon is missing the closing vertex. In order to be a valid KML polygon, the first coordinate set (lon,lat,alt) must be repeated as the last coordinate set, so that the polygon closes itself. For your example of a square, you would need 5 coordinate sets, with the first and the last being the same.
Try fixing that first, and if you still see coloring issues, try making sure that the vertex winding direction is correct (anti-clockwise). If it's backwards, then the darker "bottom" of the polygon will be facing upwards, and might appear dark/black. Yours appears correct from looking at the coordinates, but I could be mistaken.
Also, your color is not a valid KML color, as it appears to have an extra "0x" in front. A valid KML color needs four two-character values (each between 00 and ff), representing Alpha, Blue, Green, Red (AABBGGRR, and yes, it's backwards from HTML colors). A solid red would be: FF0000FF.
Below is an updated copy of your KML sample with altitudeMode = absolute, the closing vertex added, and the color corrected... this works for me in Earth Pro.
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2">
<Document id="1">
<Document id="2">
<Style id="10">
<PolyStyle id="10">
<color>FF0000FF</color>
<colorMode>normal</colorMode>
<fill>1</fill>
<outline>1</outline>
</PolyStyle>
</Style>
<name>Antenna Data</name>
<Camera>
<longitude>-122.30201334502573</longitude>
<latitude>37.87244901754293</latitude>
<altitude>200</altitude>
</Camera>
<Placemark id="5">
<name>region</name>
<styleUrl>#10</styleUrl>
<Polygon id="4">
<altitudeMode>absolute</altitudeMode>
<outerBoundaryIs>
<LinearRing id="8">
<coordinates>-122.30243999999999,37.871973499999996,10 -122.30243999999999,37.8719265,10 -122.30238,37.8719265,10 -122.30238,37.871973499999996,10 -122.30243999999999,37.871973499999996,10</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>
</Document>
</Document>
</kml>
The solution I came across was that I could simple de-activate terrain in Google Earth. This seems to work now.
<?xml version="1.0" encoding="UTF-8"?>
<kml
xmlns="http://www.opengis.net/kml/2.2"
xmlns:gx="http://www.google.com/kml/ext/2.2">
<Document>
<Style id="Line1">
<LineStyle>
<color>ffff0000</color>
<width>4</width>
</LineStyle>
</Style>
<Style id="Line2">
<LineStyle>
<color>ff00ff00</color>
<width>4</width>
</LineStyle>
</Style>
<Style id="Poly1">
<PolyStyle>
<color>ff0000ff</color>
</PolyStyle>
</Style>
<Style id="Poly2">
<PolyStyle>
<color>ffffffff</color>
</PolyStyle>
</Style>
<Placemark>
<name>Line 1</name>
<styleUrl>#Line1</styleUrl>
<LineString>
<coordinates>
-112.265654928602,36.09447672602546,2357
-112.2660384528238,36.09342608838671,2357
-112.2668139013453,36.09251058776881,2357
-112.2677826834445,36.09189827357996,2357
-112.2688557510952,36.0913137941187,2357
-112.2694810717219,36.0903677207521,2357
-112.2695268555611,36.08932171487285,2357
-112.2690144567276,36.08850916060472,2357
-112.2681528815339,36.08753813597956,2357
-112.2670588176031,36.08682685262568,2357
-112.2657374587321,36.08646312301303,2357
</coordinates>
<gx:drawOrder>2</gx:drawOrder>
</LineString>
</Placemark>
<Placemark>
<name>Polygon 1</name>
<styleUrl>#Poly1</styleUrl>
<Polygon>
<outerBoundaryIs>
<LinearRing>
<coordinates>
-112.265654928602,36.09447672602546,2357
-112.2660384528238,36.09342608838671,2357
-112.2668139013453,36.09251058776881,2357
-112.2677826834445,36.09189827357996,2357
-112.2688557510952,36.0913137941187,2357
-112.2694810717219,36.0903677207521,2357
-112.2695268555611,36.08932171487285,2357
-112.2690144567276,36.08850916060472,2357
-112.2681528815339,36.08753813597956,2357
-112.2670588176031,36.08682685262568,2357
-112.2657374587321,36.08646312301303,2357
</coordinates>
</LinearRing>
</outerBoundaryIs>
<gx:drawOrder>4</gx:drawOrder>
</Polygon>
</Placemark>
<Placemark>
<name>Line 2</name>
<styleUrl>#Line2</styleUrl>
<LineString>
<coordinates>
-112.265654928602,36.09447672602546,2357
-112.2660384528238,36.09342608838671,2357
-112.2668139013453,36.09251058776881,2357
-112.2677826834445,36.09189827357996,2357
-112.2688557510952,36.0913137941187,2357
-112.2694810717219,36.0903677207521,2357
-112.2695268555611,36.08932171487285,2357
-112.2690144567276,36.08850916060472,2357
-112.2681528815339,36.08753813597956,2357
-112.2670588176031,36.08682685262568,2357
-112.2657374587321,36.08646312301303,2357
</coordinates>
<gx:drawOrder>4</gx:drawOrder>
</LineString>
</Placemark>
<Placemark>
<name>Polygon 2</name>
<styleUrl>#Poly2</styleUrl>
<Polygon>
<outerBoundaryIs>
<LinearRing>
<coordinates>
-112.265654928602,36.09447672602546,2357
-112.2660384528238,36.09342608838671,2357
-112.2668139013453,36.09251058776881,2357
-112.2677826834445,36.09189827357996,2357
-112.2688557510952,36.0913137941187,2357
-112.2694810717219,36.0903677207521,2357
-112.2695268555611,36.08932171487285,2357
-112.2690144567276,36.08850916060472,2357
-112.2681528815339,36.08753813597956,2357
-112.2670588176031,36.08682685262568,2357
-112.2657374587321,36.08646312301303,2357
</coordinates>
</LinearRing>
</outerBoundaryIs>
<gx:drawOrder>8</gx:drawOrder>
</Polygon>
</Placemark>
</Document>
</kml>
So As you can see in the above kml I've tried to use the gx:drawOrder element to sort the line strings & the polygons into drawing layers. BUT... if you load this in the kml interactive sampler or even Google Earth (free desktop edition) the geometry primitives only z order sort among "like primitives". That is, the line strings are sorted only against other line strings and the polygons are only sorted against other polygons.
In this case you can see that both "line 1" and "line 2" have draw orders of < "Polygon 2" & I as such I was expecting "polygon 2" to draw over the top of everything. But that is NOT the case.
In the end I've had to use altitude values to implement the z order that I want, but it's quite an unsatisfactory solution as most people view kml geometry using an isometric projection & the altitude values cause my geometry to skew.
What I'd like to know is this:
Is this the expected behavior of gx:drawOrder? The document around the element is sparse & it even says that it's only applicable to the line string, but according to the xsd is should be applicable to all geometry primitives (which it appears to be... well at least to polygons as well anyway...)
Is there a way to get the gx:drawOrder to be applicable over all
geometry primitives?
Thanks in advance!
The KML documentation only mentions <gx:drawOrder> with respect to line strings not polygons nor does it mention the behavior of drawOrder across different geometries (lines, rings, and polygons). The drawOrder support for Polygons is undocumented but was reported as an issue in the bug tracker.
You would naturally expect the drawOrder to work the same over all geometry primitives, but looks like Google Earth draws the features in groups by type: polygons, then ground overlays, followed by lines and point data where drawOrder is applied only within a group. ScreenOverlays are drawn last so they are always on top.
This means that a polygon with drawOrder=2 overlapping a line with drawOrder=1 still shows the polygon under the line. Also, even if a polygon has a higher value drawOrder and overlaps a GroundOverlay (aka Image Overlay), the polygon is drawn first and hidden under the GroundOverlay.
gx:DrawOrder is not part of the OGC KML 2.2 standard. It's a Google KML Extension so Google defines how it works. Also means Google can change how it works.
I have adjacent polygons (clampToGround) where a portion of the boundaries overlap. I would like to be able to control which one appears on top. The only method I've found to work thus far is to list the polygon placemarks in stack order (last on list appears on top). However, I'd like to organize the placemarks based on other logic and would like a coding method to specify which polygon is on top.
Note, I've also tried using relativeToGround and small elevation differences, but that leads to potions of the polygons fill to disappear beneath the topography.
You can specify <gx:drawOrder> element (which is a Google Earth KML extension) to order polygons as well as lines and rings in your KML.
Note the documentation (see below) only specifies LineStrings but also works for Lines, LinearRings, and Polygons. Anywhere "LineStrings" is mentioned below just replace it with Lines, Rings, and Polygons. The drawOrder support for Polygons is undocumented but was reported as an issue.
KML Documentation:
<gx:drawOrder>
"An integer value that specifies the order for drawing multiple line
strings. LineStrings drawn first may be partially or fully obscured by LineStrings with a later (or higher) draw order. This element may be required in
conjunction with the <gx:outerColor> and <gx:outerWidth> elements in
<LineStyle> when dual-colored lines cross each other."
Note this will only work in clients that support the Google Earth KML extensions.
In example below, the Red polygon is drawn over the blue polygon. To make the blue polygon draw over the red one change its drawOrder value to a higher number.
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2">
<Document>
<Placemark>
<name>Red Polygon</name>
<description>gx:drawOrder=3</description>
<Style>
<LineStyle>
<color>ff000000</color>
</LineStyle>
<PolyStyle>
<color>ff0000ff</color>
</PolyStyle>
</Style>
<Polygon>
<gx:drawOrder>3</gx:drawOrder>
<tessellate>1</tessellate>
<outerBoundaryIs>
<LinearRing>
<coordinates>
14.456906,37.345497,0 14.949769,37.346531,0
14.960918,37.987563,0 14.45089,37.987521,0
14.456906,37.3455,0
</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>
<Placemark>
<name>Blue Polygon</name>
<description>gx:drawOrder=2</description>
<Style>
<LineStyle>
<color>ff000000</color>
</LineStyle>
<PolyStyle>
<color>ffff0000</color>
</PolyStyle>
</Style>
<Polygon>
<gx:drawOrder>2</gx:drawOrder>
<tessellate>1</tessellate>
<outerBoundaryIs>
<LinearRing>
<coordinates>
14.83626,38.016863,0 14.835535,37.645589,0
15.47025,37.589266,0 15.470457,38.019158,0
14.83626,38.016862,0
</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</Placemark>
</Document>
</kml>
I have asked to keep polygon, name of the polygon and the corresponding icon in the places panel.
Can any suggest me how to do this in kml?
By default you only see the name label if your placemark has a Point geometry so for lines and polygons the name is not shown.
You can however create a MultiGeometry with both a Polygon and a Point (typically the center point or where you want to label to appear near). If you don't want the default yellow pushpin to appear just add a Style with an empty IconStyle href element to the Placemark.
<?xml version="1.0" encoding="utf-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
<Placemark>
<name>polygon</name>
<Style>
<IconStyle>
<Icon/>
</IconStyle>
</Style>
<MultiGeometry>
<Point>
<coordinates>-122.4317195,37.801848</coordinates>
</Point>
<Polygon>
<outerBoundaryIs>
<LinearRing>
<coordinates>
-122.43193945401,37.801983684521
-122.431564131101,37.8020327731402
-122.431499536494,37.801715236748
-122.43187136387,37.8016634915437
-122.43193945401,37.801983684521
</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</MultiGeometry>
</Placemark>
</kml>
This multi-geometry method can be HIGHLY tedious if you have a couple hundred polygons (say, a grid/index) and you want to show their names.
My preference is to use something like QGIS/Arc, where I create a new vector file of polygon centroids (point file) that has the polygon attributes (including name/description). I save the new point file as a point KML and import into Google Earth. From their, I set a shared style for the point file, with the icon set to 0% opacity.
Example of Google Earth Polygons with Labels using above method
I am pretty accomplished at using the animated update function of google earth and am using it to move models around. What I would really like to do is to be able to animate a line (eg up and down) in Google Earth but am finding this tricky.
I have the longitude and latitude of the line at the start. For example line coordinates are:
-88,17,100 -88.20270841086835,17.21899813162266,100
I then want to raise one end of this line up to an altitude of 500 over a period of 5 seconds.
I've drawn the line using LineString:
<Placemark id="path1">
<name>Untitled Path man</name>
<LineString>
<tessellate>1</tessellate>
<coordinates>
-88.,17,100 -88.20270841086835,17.21899813162266,100
</coordinates>
</LineString>
</Placemark>
But Im now lost as to how to use <gx:AnimatedUpdate> to move one end up from 100 to 500.
Im sure its easy - can someone point me in the right direction??
The trick is to update the LineString element (with an id on that) rather than the Placemark.
Here's a working KML example tour that animates a line changing from a relative altitude of 100 to 500m.
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2">
<Document>
<name>gx:AnimatedUpdate example</name>
<open>1</open>
<LookAt>
<longitude>-88.1351880996469</longitude>
<latitude>17.09943637744042</latitude>
<altitude>0</altitude>
<heading>49.91874373078863</heading>
<tilt>84.43764019949967</tilt>
<range>1929.311316966288</range>
<gx:altitudeMode>relativeToSeaFloor</gx:altitudeMode>
</LookAt>
<Placemark>
<name>Untitled Path man</name>
<LineString id="path1">
<tessellate>1</tessellate>
<altitudeMode>relativeToGround</altitudeMode>
<coordinates>
-88,17,100 -88.20270841086835,17.21899813162266,100
</coordinates>
</LineString>
</Placemark>
<gx:Tour>
<name>Play me!</name>
<gx:Playlist>
<gx:AnimatedUpdate>
<gx:duration>5</gx:duration>
<Update>
<targetHref/> <!-- Left empty to refer to the current file -->
<Change>
<LineString targetId="path1">
<coordinates>
-88,17,100 -88.20270841086835,17.21899813162266,500
</coordinates>
</LineString>
</Change>
</Update>
</gx:AnimatedUpdate>
<!-- Wait for the animation to complete (see the touring
tutorial for an explanation of how AnimatedUpdate's
duration isn't enough to guarantee this). -->
<gx:Wait>
<gx:duration>5.0</gx:duration>
</gx:Wait>
</gx:Playlist>
</gx:Tour>
</Document>
</kml>
For details see https://developers.google.com/kml/documentation/touring#tourtimelines