<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:"Gill Sans MT";
panose-1:2 11 5 2 2 1 4 2 2 3;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
span.E-postmall18
{mso-style-type:personal-reply;
font-family:"Gill Sans MT",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;
mso-fareast-language:EN-US;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:70.85pt 70.85pt 70.85pt 70.85pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-GB" link="blue" vlink="purple" style="word-wrap:break-word">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif;mso-fareast-language:EN-US">Yes, you can transform the position from the GNSS-receiver directly to XYZ with
</span><span style="font-family:"Courier New";color:black;background:white">cct +proj=cart +ellps=GRS80</span><span style="font-family:"Arial",sans-serif;color:black;background:white"> . I</span><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif;mso-fareast-language:EN-US">t
does not make any sense to transform from WGS84 to SWEREF 99 first. The difference between SWEREF 99 and WGS84 is today about 8 dm, and your position from the GNSS-receiver has probably a larger uncertainty, so it does not matter if you use WGS84 or SWEREF
99 for the virtual location. But in the GNSS-processing with the virtual RINEX-file the coordinates are considered as accurate SWEREF 99-coordinates.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif;mso-fareast-language:EN-US">Best Regards, Lotti<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="SV">Från:</span></b><span lang="SV"> Roger Oberholtzer <roger.oberholtzer@gmail.com>
<br>
<b>Skickat:</b> den 21 april 2022 11:27<br>
<b>Till:</b> Jivall Lotti <Lotti.Jivall@lm.se><br>
<b>Kopia:</b> PROJ <PROJ@lists.osgeo.org><br>
<b>Ämne:</b> Re: [PROJ] Sweref99 Cartesian<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">On Thu, Apr 21, 2022 at 9:39 AM Jivall Lotti <<a href="mailto:Lotti.Jivall@lm.se">Lotti.Jivall@lm.se</a>> wrote:<o:p></o:p></p>
</div>
<div>
<blockquote style="border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;margin-left:4.8pt;margin-right:0cm">
<div>
<div>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif">Hi Roger,
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif">SWEREF 99 is a 3D geodetic reference system (the Swedish realisation of ETRS89) and can be expressed as geocentric
cartesian coordinates (X Y Z) , geodetic coordinates (latitude, longitude and height) or a number of map projections where SWEREF 99 TM is the national one (whole Sweden in one zone). You can read more at
<a href="https://www.lantmateriet.se/en/maps-and-geographic-information/gps-geodesi-och-swepos/Referenssystem/Tredimensionella-system/SWEREF-99/" target="_blank">
Lantmäteriets webb page</a>. </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif">You are right that SWEPOS virtual RINEX generator is requesting SWEREF 99 XYZ (and I understand it might be
easier for you to use PROJ instead of out online transformation on the webb). All SWEPOS services are producing data in SWEREF 99, as this is the national reference frame. It means that when you process your GNSS-observations with the VRS reference data then
you will get the results in SWEREF 99. (Therefore you should <b>not</b> use the accurate NKG-transformation from ITRF2014 (WGS84) to SWEREF 99 – if your final results should be presented in SWEREF 99!)</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif">Your original position from the GNSS-receiver is in WGS84 (current epoch) but I guess just on a few meter level
and actually you just need a very approximate position to get your virtual reference near your own measurements. The position you input to SWEPOS VRS generator will be interpreted as SWEREF 99.
</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:12.0pt;font-family:"Gill Sans MT",sans-serif">Hope it is now more clear!</span><o:p></o:p></p>
</div>
</div>
</blockquote>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">I think so. So you mean if I provide the receiver's WGS84 lat/lng to, say,
<span style="font-family:"Courier New";color:black;background:white">cct +proj=cart +ellps=GRS80</span><span style="font-family:"Arial",sans-serif;color:black;background:white"> , then the resulting locations should be adequate for requesting a virtual station
at that WGS84 location?</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
<p class="MsoNormal">-- <o:p></o:p></p>
<div>
<p class="MsoNormal">Roger Oberholtzer<o:p></o:p></p>
</div>
</div>
</div>
</body>
</html>