Stuart Robinson


Help!

I am attempting to overlay US Radar images on a VE Map. The images in transparent gif format can be sourced free from here
http://www.srh.noaa.gov/jetstream/remote/ridge_download.htm

I can also generate KMZ / KML definition files from here
http://www.srh.noaa.gov/ridge/kmzgenerator.php

by taking apart a kml file I know the URL and the lon/lat bounds of the image
for example the radar Dallas is http://www.srh.noaa.gov/ridge/RadarImg/N0Z/FWS_N0Z_0.gif

with the upper bounds of the image being..

<north>36.5657291342995</north>
<south>28.5657291343</south>
<east>-92.932092312899</east>
<west>-101.659365040172</west>

So I know the lon/lat edges and corner of the file – I guess that I could somewhere online find the lon/lat centre of the radar as well.

Question is how to use this in VE

Knowing the centre and edges of my VE map I could easily display a pushpin image of the radar gif – this would handle scroll etc – but how then to handle zoom as the image need to stretch or compress – I can control the image resize using the pushpin ccs height, width and clip!

It is a shame that I can not just pin the corners of the image to four lon/lats.

Before I get into this – has anyone done some thing similar before or can suggest an alternative way of doing it – which does NOT involve using Google maps – when native KMZ / KML is supported.

Thanks in advance for all that reply




Re: Suggestion Req. – how to overlay USA Radar?

FixingTheHoleInTheOcean


Interesting question... I don't have a solution for you, just some notes.

- The ridge site says that the images are provided in geographic projection, nad 83 (lat/lon). Virtual Earth expects tiles in Mercator projection, so you'll have to reproject the images you're getting if you want to use them from a tile server.

- Seems like you'll have to reproject anyway, since trying to overlay the lat/lon data in any way is going to give bad results.

- I've been playing with SharpMap as a dynamic TileSource, but only for vector files and some rasters that were already in mercator projection. I'm not sure if it will reproject raster images on the fly.

- I assume that you'll want this thing to always display the most up-to-date radar images So any solution involving MapCruncher is unusable.

- The full coverage image of the US is available here http://www.srh.noaa.gov/ridge/Conus/RadarImg/ and called "latest_radaronly.gif", along with it's world file "latest_radaronly.gfw







Re: Suggestion Req. – how to overlay USA Radar?

FixingTheHoleInTheOcean

Oops, just noticed something - mapcruncher can be run from the command line, so it might be possible to set up a script that periodically downloads new radar images and their corner coordinates, generates a mapcruncher config file, runs mapcruncher, and then overwrites the old tiles with the fresh ones.

Kind of a roundabout way of doing things, but it may be the easiest way.







Re: Suggestion Req. – how to overlay USA Radar?

Stuart Robinson

I had 1/2 hour at work so I tried mapCruncher approch - I could get the radar to display with correct zoom but I get the dreaded black lines across the screen on IE7. Apparently this is known fault with MC - but with out work around since November :(

Also I was unable to get MC to render via a script using the -render switch.

However I will look at this again tonight at home.

It may have to accept that I will not be able to display radar....





Re: Suggestion Req. – how to overlay USA Radar?

Brian_Flood

hi all

i will echo your IE transparency issue, IMO this is huge problem with VE and custom map tiles. They look horrible in IE, I hope they get this squared away as quick as possible

on another note, we are now beta testing Arc2Earth Publisher. It requires ArcGIS but it may be an option for some people. It creates map tiles, marker layers and viewers for VE, Google and OpenLayers. One thing to note is that it exports "continuous" maps, that is it works with the ArcMap extent directly and not through an intermediary image file. This is important for multiple map levels since the quality of the tiles will degrade with a single image source whereas A2E will continually refresh the map so that the best resolution (and scale dependent symbols) are rendered.

here's some screen grabs of the various viewers, we hope to have this product out by next month

Florida Radar sample (3 minute export, published automatically to Amazon S3)

VE 2D (firefox so the black lines aren't there :) )

http://www.spatialdatalogic.com/sdl/public/images/radar_VE2D.png 

VE 3D

http://www.spatialdatalogic.com/sdl/public/images/radar_VE3D2.png

Google Maps

http://www.spatialdatalogic.com/sdl/public/images/radar_GM.png

Google Earth

http://www.spatialdatalogic.com/sdl/public/images/radar_GE.png






Re: Suggestion Req. – how to overlay USA Radar?

SoulSolutions

Nice work Brian!

I will definitely be in touch with you next month. Looks like you have a good product there.

John.






Re: Suggestion Req. – how to overlay USA Radar?

Stuart Robinson

Very Godd Brian,

 

If only we could resolve the black line issue then your product will work for me! - I will be in touch too.





Re: Suggestion Req. – how to overlay USA Radar?

SoulSolutions

Not this fix by any chance

http://www.lewisharvey.net/blog/ p=29

John.






Re: Suggestion Req. – how to overlay USA Radar?

Brian_Flood

that fix sorta works and while clever, its not the best way to solve the problem. IMO, the VE team needs to fix the root cause.

for instance, the fix above listens for the view to change and then applies the fix. so the user sees the streaked tiles for a second. likewise, some zooming techniques seem to skip the viewchanged event (scroll wheel). all in all, it doesn't seem reliable enough to use in production.

here's what it looks like in IE6: http://www.spatialdatalogic.com/sdl/public/images/bustedVE.png Sometimes all of the tiles will get converted but ehy are still not transparent.

finally, there must be a viable fix to display these tiles since they show up fine in GMaps in IE6/7.

cheers

brian






Re: Suggestion Req. – how to overlay USA Radar?

SoulSolutions

Agreed, it needs to be fixed by the VE team,

Now, i am right to assume that the technique used for FF would work for IE7

If so maybe it is possible to look at where the decision is made in the VE logic and modify it to direct IE7 down the right path

John.






Re: Suggestion Req. – how to overlay USA Radar?

Brian_Flood

i get the black streaks in IE6 and IE7, so it needs to be fixed all around. my point was the gmaps guys got it working for both so its definitely possible. To be honest, I can't believe they haven't fixed it yet, it's been quite awhile and this must affect the MapCruncher layers as well

cheers

brian






Re: Suggestion Req. – how to overlay USA Radar?

Derek Chan

Brian_Flood wrote:

i get the black streaks in IE6 and IE7, so it needs to be fixed all around. my point was the gmaps guys got it working for both so its definitely possible. To be honest, I can't believe they haven't fixed it yet, it's been quite awhile and this must affect the MapCruncher layers as well

cheers

brian



Correct, it affects mapcruncher layers, and there isn't a resolution yet: Info here and a great screenshot of what your seeing at this link:

http://research.microsoft.com/mapcruncher/tutorial/version3.0docs/index.htm#_Toc148418545