Re: [Xastir] Tiger 2007 shapefile issue...a beaut
Now decorrelate the GPGLL sentences from the 4-hr test by decimating to 30- or 60-second intervals. Decorrelation really does help. Average, then use a least-squares method to determine residual error. I don't use choke-rings or ground planes when doing kinematic work. We do make sure the antenna is aligned to N when we do it, though, as pattern will affect results. Finnegan's Finagiling Factor (also called "bias" in literature) has saved my butt a bunch of times in the field. I do a version of that in post-processing, too, but the whole procedure is best described in a journal article or over a beer. Or both. Richard Polivka, N6NKO wrote: Alright, here are the details of the equipment: - About 7' of 1.25" PVC pipe with a hole through it for a rubber band to hold onto GPS unit - US GlobalSat BT-359 Bluetooth GPS receiver - chipset: SiRF STAR-III/LP - Cingular 8525 smartphone - "Turbo GPS" software Ver 2.00 alpha 8 Did testing in NMEA mode. SiRF mode has the longitude really messed up. I think I will hit up a couple of BM's and see how bad the data is. Maybe it may be recoverable by applying Finnegan's Fudge Factor. Trying to resolve a garbage can using just L1 and a consumer grade GPS will just give you garbage when you have only ddmm. to use. I went in knowing what the maximum resolution is: one count latitude = 0. meters; one count longitude = 0.1630 meters. I was willing to spot the rig +/- five counts moving so I would say that I made my self-imposed limit. I thought that it would be worse. Using a 2m range pole with a surgical sharp pick at the end will do your feet some damage. You probably have a outrageously overpriced choke ring antenna on top and that in itself is a real headknocker in its own right. I did a test with this setup here at home one day over four hours. I pulled out the NMEA $GPGLL sentences that were at PDOP= 0.6 and mapped them out. The resulting x-y graph presented an almost circular pattern of a diameter of 8 counts. Averaging the readings put the average right in the middle of the chart. I am quite happy with this mashup. Not professional grade but it will do the jobs that I need it to do. Have a good week. Now to pull up a property survey to figure out an issue for someone. Best Regards, Richard, N6NKO Gerry Creager wrote: Richard Polivka, N6NKO wrote: Gerry, Yes, the coffee has kicked in and I had egg-on-face for breakfast. The map in QGIS looks just like the same as the aforementioned area when at full extent view. Zoomed in, it works. The egg comment has to do with a Census screwup... It's Census, it's gonna happen. Their view of GIS has been "interesting" for some time. I am glad you got it to work! Error budget - Well, I am within 5 ft on backtracked trails. Can't complain for working under a tree canopy. 1.8m isn't bad, at all! Now: Imagine what happens when your typical error is 2-3 meters, and a picnic table is smaller in at least one dimension is smaller than the error budget. The geometry is, well, interesting, and usually looks more like a bow-tie than a rectangle. Getting several points to define the radius of a trash can gets even more entertaining. I had the GPS unit on top of a 7 ft PVC pipe talking to my smartphone over bluetooth. I just ran out of time to cover the whole place but the proof of concept pans out. When I go do this stuff, I use a 2m "range" pole. a fixed height fiberglas and metal deal designed to poke holes in shoes and give one a good feel that their antenna is exactly this high above the point in question. We also have a bulls-eye level on it to allow us to get it spot-on above the point in question. Your rig sounds easier to work with. gerry Now its off to other work tasks. 73 from 807, Richard, N6NKO Gerry Creager wrote: Richard Polivka, N6NKO wrote: Gerry, Good morning! I realize that wholeheartedly, but to have this big of a screwupoh, wait, this is the Federal Government Aha! Your coffee kicked in? What hardware are you using for your campground survey? I can tell you stories about those from several years ago, when folks were trying to resolve objects (e.g., a picnic table) that was smaller than their uncorrected L1 error budget... gerry Gerry Creager wrote: Richard Polivka, N6NKO wrote: I admit that one point does not make a trend but what I found was eyeopening. I wanted just Fond du Lac county in Wisconsin to use as a base map for mapping project that I am working on ( a Boy Scout campground). I pulled in my files into QGIS and then brought in "fe_2007_55039_edges". I did not get Fond du Lac County but a huge overview of north Illinois, Indiana and SE Michigan. OUCH!!! I even went and downloaded a virgin fileset and got the same results (see picture). 55039.png This is not good. I plan on sending on a comment to the Census Bureau. So, let the user beware - YMMV. Unfortunately, this warning ha
Re: [Xastir] Tiger 2007 shapefile issue...a beaut
Alright, here are the details of the equipment: - About 7' of 1.25" PVC pipe with a hole through it for a rubber band to hold onto GPS unit - US GlobalSat BT-359 Bluetooth GPS receiver - chipset: SiRF STAR-III/LP - Cingular 8525 smartphone - "Turbo GPS" software Ver 2.00 alpha 8 Did testing in NMEA mode. SiRF mode has the longitude really messed up. I think I will hit up a couple of BM's and see how bad the data is. Maybe it may be recoverable by applying Finnegan's Fudge Factor. Trying to resolve a garbage can using just L1 and a consumer grade GPS will just give you garbage when you have only ddmm. to use. I went in knowing what the maximum resolution is: one count latitude = 0. meters; one count longitude = 0.1630 meters. I was willing to spot the rig +/- five counts moving so I would say that I made my self-imposed limit. I thought that it would be worse. Using a 2m range pole with a surgical sharp pick at the end will do your feet some damage. You probably have a outrageously overpriced choke ring antenna on top and that in itself is a real headknocker in its own right. I did a test with this setup here at home one day over four hours. I pulled out the NMEA $GPGLL sentences that were at PDOP= 0.6 and mapped them out. The resulting x-y graph presented an almost circular pattern of a diameter of 8 counts. Averaging the readings put the average right in the middle of the chart. I am quite happy with this mashup. Not professional grade but it will do the jobs that I need it to do. Have a good week. Now to pull up a property survey to figure out an issue for someone. Best Regards, Richard, N6NKO Gerry Creager wrote: Richard Polivka, N6NKO wrote: Gerry, Yes, the coffee has kicked in and I had egg-on-face for breakfast. The map in QGIS looks just like the same as the aforementioned area when at full extent view. Zoomed in, it works. The egg comment has to do with a Census screwup... It's Census, it's gonna happen. Their view of GIS has been "interesting" for some time. I am glad you got it to work! Error budget - Well, I am within 5 ft on backtracked trails. Can't complain for working under a tree canopy. 1.8m isn't bad, at all! Now: Imagine what happens when your typical error is 2-3 meters, and a picnic table is smaller in at least one dimension is smaller than the error budget. The geometry is, well, interesting, and usually looks more like a bow-tie than a rectangle. Getting several points to define the radius of a trash can gets even more entertaining. I had the GPS unit on top of a 7 ft PVC pipe talking to my smartphone over bluetooth. I just ran out of time to cover the whole place but the proof of concept pans out. When I go do this stuff, I use a 2m "range" pole. a fixed height fiberglas and metal deal designed to poke holes in shoes and give one a good feel that their antenna is exactly this high above the point in question. We also have a bulls-eye level on it to allow us to get it spot-on above the point in question. Your rig sounds easier to work with. gerry Now its off to other work tasks. 73 from 807, Richard, N6NKO Gerry Creager wrote: Richard Polivka, N6NKO wrote: Gerry, Good morning! I realize that wholeheartedly, but to have this big of a screwupoh, wait, this is the Federal Government Aha! Your coffee kicked in? What hardware are you using for your campground survey? I can tell you stories about those from several years ago, when folks were trying to resolve objects (e.g., a picnic table) that was smaller than their uncorrected L1 error budget... gerry Gerry Creager wrote: Richard Polivka, N6NKO wrote: I admit that one point does not make a trend but what I found was eyeopening. I wanted just Fond du Lac county in Wisconsin to use as a base map for mapping project that I am working on ( a Boy Scout campground). I pulled in my files into QGIS and then brought in "fe_2007_55039_edges". I did not get Fond du Lac County but a huge overview of north Illinois, Indiana and SE Michigan. OUCH!!! I even went and downloaded a virgin fileset and got the same results (see picture). 55039.png This is not good. I plan on sending on a comment to the Census Bureau. So, let the user beware - YMMV. Unfortunately, this warning has always been necessary with TIGER files. They're not the best GIS data source. They're just available and free. ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Tiger 2007 shapefile issue...a beaut
Richard Polivka, N6NKO wrote: Gerry, Yes, the coffee has kicked in and I had egg-on-face for breakfast. The map in QGIS looks just like the same as the aforementioned area when at full extent view. Zoomed in, it works. The egg comment has to do with a Census screwup... It's Census, it's gonna happen. Their view of GIS has been "interesting" for some time. I am glad you got it to work! Error budget - Well, I am within 5 ft on backtracked trails. Can't complain for working under a tree canopy. 1.8m isn't bad, at all! Now: Imagine what happens when your typical error is 2-3 meters, and a picnic table is smaller in at least one dimension is smaller than the error budget. The geometry is, well, interesting, and usually looks more like a bow-tie than a rectangle. Getting several points to define the radius of a trash can gets even more entertaining. I had the GPS unit on top of a 7 ft PVC pipe talking to my smartphone over bluetooth. I just ran out of time to cover the whole place but the proof of concept pans out. When I go do this stuff, I use a 2m "range" pole. a fixed height fiberglas and metal deal designed to poke holes in shoes and give one a good feel that their antenna is exactly this high above the point in question. We also have a bulls-eye level on it to allow us to get it spot-on above the point in question. Your rig sounds easier to work with. gerry Now its off to other work tasks. 73 from 807, Richard, N6NKO Gerry Creager wrote: Richard Polivka, N6NKO wrote: Gerry, Good morning! I realize that wholeheartedly, but to have this big of a screwupoh, wait, this is the Federal Government Aha! Your coffee kicked in? What hardware are you using for your campground survey? I can tell you stories about those from several years ago, when folks were trying to resolve objects (e.g., a picnic table) that was smaller than their uncorrected L1 error budget... gerry Gerry Creager wrote: Richard Polivka, N6NKO wrote: I admit that one point does not make a trend but what I found was eyeopening. I wanted just Fond du Lac county in Wisconsin to use as a base map for mapping project that I am working on ( a Boy Scout campground). I pulled in my files into QGIS and then brought in "fe_2007_55039_edges". I did not get Fond du Lac County but a huge overview of north Illinois, Indiana and SE Michigan. OUCH!!! I even went and downloaded a virgin fileset and got the same results (see picture). 55039.png This is not good. I plan on sending on a comment to the Census Bureau. So, let the user beware - YMMV. Unfortunately, this warning has always been necessary with TIGER files. They're not the best GIS data source. They're just available and free. ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir -- Gerry Creager -- [EMAIL PROTECTED] Texas Mesonet -- AATLT, Texas A&M University Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983 Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843 ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Tiger 2007 shapefile issue...a beaut
Gerry, Yes, the coffee has kicked in and I had egg-on-face for breakfast. The map in QGIS looks just like the same as the aforementioned area when at full extent view. Zoomed in, it works. Error budget - Well, I am within 5 ft on backtracked trails. Can't complain for working under a tree canopy. I had the GPS unit on top of a 7 ft PVC pipe talking to my smartphone over bluetooth. I just ran out of time to cover the whole place but the proof of concept pans out. Now its off to other work tasks. 73 from 807, Richard, N6NKO Gerry Creager wrote: Richard Polivka, N6NKO wrote: Gerry, Good morning! I realize that wholeheartedly, but to have this big of a screwupoh, wait, this is the Federal Government Aha! Your coffee kicked in? What hardware are you using for your campground survey? I can tell you stories about those from several years ago, when folks were trying to resolve objects (e.g., a picnic table) that was smaller than their uncorrected L1 error budget... gerry Gerry Creager wrote: Richard Polivka, N6NKO wrote: I admit that one point does not make a trend but what I found was eyeopening. I wanted just Fond du Lac county in Wisconsin to use as a base map for mapping project that I am working on ( a Boy Scout campground). I pulled in my files into QGIS and then brought in "fe_2007_55039_edges". I did not get Fond du Lac County but a huge overview of north Illinois, Indiana and SE Michigan. OUCH!!! I even went and downloaded a virgin fileset and got the same results (see picture). 55039.png This is not good. I plan on sending on a comment to the Census Bureau. So, let the user beware - YMMV. Unfortunately, this warning has always been necessary with TIGER files. They're not the best GIS data source. They're just available and free. ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Tiger 2007 shapefile issue...a beaut
Richard Polivka, N6NKO wrote: Gerry, Good morning! I realize that wholeheartedly, but to have this big of a screwupoh, wait, this is the Federal Government Aha! Your coffee kicked in? What hardware are you using for your campground survey? I can tell you stories about those from several years ago, when folks were trying to resolve objects (e.g., a picnic table) that was smaller than their uncorrected L1 error budget... gerry Gerry Creager wrote: Richard Polivka, N6NKO wrote: I admit that one point does not make a trend but what I found was eyeopening. I wanted just Fond du Lac county in Wisconsin to use as a base map for mapping project that I am working on ( a Boy Scout campground). I pulled in my files into QGIS and then brought in "fe_2007_55039_edges". I did not get Fond du Lac County but a huge overview of north Illinois, Indiana and SE Michigan. OUCH!!! I even went and downloaded a virgin fileset and got the same results (see picture). 55039.png This is not good. I plan on sending on a comment to the Census Bureau. So, let the user beware - YMMV. Unfortunately, this warning has always been necessary with TIGER files. They're not the best GIS data source. They're just available and free. ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir -- Gerry Creager -- [EMAIL PROTECTED] Texas Mesonet -- AATLT, Texas A&M University Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983 Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843 ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Tiger 2007 shapefile issue...a beaut
Gerry, Good morning! I realize that wholeheartedly, but to have this big of a screwupoh, wait, this is the Federal Government 73 from 807, Richard Gerry Creager wrote: Richard Polivka, N6NKO wrote: I admit that one point does not make a trend but what I found was eyeopening. I wanted just Fond du Lac county in Wisconsin to use as a base map for mapping project that I am working on ( a Boy Scout campground). I pulled in my files into QGIS and then brought in "fe_2007_55039_edges". I did not get Fond du Lac County but a huge overview of north Illinois, Indiana and SE Michigan. OUCH!!! I even went and downloaded a virgin fileset and got the same results (see picture). 55039.png This is not good. I plan on sending on a comment to the Census Bureau. So, let the user beware - YMMV. Unfortunately, this warning has always been necessary with TIGER files. They're not the best GIS data source. They're just available and free. ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
Re: [Xastir] Tiger 2007 shapefile issue...a beaut
Richard Polivka, N6NKO wrote: I admit that one point does not make a trend but what I found was eyeopening. I wanted just Fond du Lac county in Wisconsin to use as a base map for mapping project that I am working on ( a Boy Scout campground). I pulled in my files into QGIS and then brought in "fe_2007_55039_edges". I did not get Fond du Lac County but a huge overview of north Illinois, Indiana and SE Michigan. OUCH!!! I even went and downloaded a virgin fileset and got the same results (see picture). 55039.png This is not good. I plan on sending on a comment to the Census Bureau. So, let the user beware - YMMV. Unfortunately, this warning has always been necessary with TIGER files. They're not the best GIS data source. They're just available and free. -- Gerry Creager -- [EMAIL PROTECTED] Texas Mesonet -- AATLT, Texas A&M University Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983 Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843 ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
[Xastir] Tiger 2007 shapefile issue...a beaut
I admit that one point does not make a trend but what I found was eyeopening. I wanted just Fond du Lac county in Wisconsin to use as a base map for mapping project that I am working on ( a Boy Scout campground). I pulled in my files into QGIS and then brought in "fe_2007_55039_edges". I did not get Fond du Lac County but a huge overview of north Illinois, Indiana and SE Michigan. OUCH!!! I even went and downloaded a virgin fileset and got the same results (see picture). 55039.png This is not good. I plan on sending on a comment to the Census Bureau. So, let the user beware - YMMV. 73 from 807, Richard, N6NKO ___ Xastir mailing list Xastir@xastir.org http://lists.xastir.org/cgi-bin/mailman/listinfo/xastir
