SRID and new feature - ScaleBar

Question

Question #1
================================================
How does ScaleBar calculate its length in meters?
Where it takes SRID for this calculation?
Assuming we have two points
Point A:
latitude 37.538476361386145 degrees
longitude 55.66146534653465
Point B:
latitude 37.53901472772277
longitude 55.66146534653465
When i issue SQL query to Oracle Spatial:
select SDO_GEOM.SDO_LENGTH(MDSYS.SDO_GEOMETRY(2003,8192,NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1,1003,1),MDSYS.SDO_ORDINATE_ARRAY(37.538476361386145,55.66146534653465,37.53901472772277,55.66146534653465 )),0.0005,'unit=M') from dual
It returns that there are about 33 meters between this points. When i looking on the map - it seems to be true.
But Scale bar on the same map request says that there are 60 meters between these two points!
Question #2
==============================================
In mapViewerConfig.xml we have an option
rendering allow_local_adjustment="true"
Previous version of MapViewer have been correctly transforming base image theme according their SRID.
New version of MapViewer seems to be render my image theme in rectangular projection and do not take into account that on this latitude: 1 degree of longitude twice smaller than 1 degree of latutude.
As a result i have output image doubled by horisontal axis. And I don`t know how to make MapViewer render my image correctly :(
Setting up rendering allow_local_adjustment="false" reveals absolutely no difference in output :(
Can someone help me with this issue? I have all my map improperly transformed by horisontal axis and it looks very terrible ....
May be first issue with Scale bar someway connected with second issue with incorrect horisontal transformation?

Answer 1

Well, Im summarizing my two questions:
1) Problems with Scale Bar length - it displays twice longer than distance obtained through SDO_GEOM.SDO_LENGTH function.
2) Problem with incorrect horizontal scaling of my map image in 11 version of MapViewer (rendering allow_local_adjustment="true")
and I will try to explain what I`m exactly doing concerning second question
Test Data:
1) I have all my spatial tables, and metadata views (user_sdo_geom._metadata) converted to SRID 8307 now. Rebuild all indexes.
2) I have EMPTY USER_SDO_MAPS and USER_SDO_THEMES tables , coz I`m usually using only dynamic themes.
GEO_RASTER table contains one square image (width=1064 and height=850 in pixels)
MBR = MDSYS.SDO_GEOMETRY(3,8307,NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1,3,1), MDSYS.SDO_ORDINATE_ARRAY(37,5368,55.6597, 37.5408,55.6615))
==================================================================
TEST #1 ( MapViewer 10, allow_local_adjustment = true, dynamic image theme)
Server startup output
06/04/06 10:12:33 WARN [oracle.lbs.mapserver.core.MapperConfig] SDOVIS local adjustment on geodetic data: ON.
Adding only one image theme to map request without specifying “master” SRID
mv.deleteAllThemes();
mv.addImageTheme(
"devtest4030",
"image_theme_test",
"SELECT BASEMAP,GEO FROM geo_raster",
"BASEMAP","GEO","GIF", "8307",false);
mv.run();
<map_request
datasource="devtest4030"
width="463"
height="404"
bgcolor="#a6caf0"
antialiase="true"
format="JAVA_IMAGE_COMPRESSED">
<center size="0.0025">
<geoFeature>
<geometricProperty typeName="center">
<Point>
<coordinates>37.5383,55.6605</coordinates>
</Point>
</geometricProperty>
</geoFeature>
</center>
<themes>
<theme name="image_theme_test">
<jdbc_image_query
image_column="BASEMAP"
image_mbr_column="GEO"
image_format="GIF"
jdbc_srid="8307"
datasource="devtest4030"
asis="false">SELECT BASEMAP,GEO FROM geo_raster </jdbc_image_query>
</theme>
</themes>
</map_request>
Test result: Redering OK. I receive correct map image. No horizontal distortion.
==============================================================
TEST #2 (MapViewer 10. , allow_local_adjustment = FALSE, dynamic image theme)
Same as above but allow_local_adjustment = FALSE
Test result: I`m observing horizontal distortion of map image. Width of image nearly twice bigger than height.
==============================================================
TEST #3 (MapViewer 10, allow_local_adjustment = FALSE, dynamic image theme, master SRID)
Now in addition to TEST #2 I try to set up projected CS as was recommended by lqian.
mv.deleteAllThemes();
mv.setMapRequestSRID(32771);
mv.addImageTheme(
"devtest4030",
"image_theme_test",
"SELECT BASEMAP,GEO FROM geo_raster",
"BASEMAP","GEO","GIF", "8307",false);
mv.run();
I received error in server output:
06/04/06 10:34:38 INFO [oracle.sdovis.theme.itp] [ImageTheme] query: SELECT * FROM ( SELECT BASEMAP,GEO FROM geo_raster) WHERE MDSYS.SDO_FILTER(GEO, MDSYS.SDO_GEOMETRY(2003, 8307, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1, 1003, 3),MDSYS.SDO_ORDINATE_ARRAY(37.53599183168317,55.65925,37.54060816831683,55.66175)), 'querytype=WINDOW') = 'TRUE'
06/04/06 10:34:39 INFO [oracle.sdovis.DBMapMaker] **** time spent on loading features: 937ms.
06/04/06 10:34:40 INFO [oracle.sdovis.DBMapMaker] **** time spent on rendering: 219ms
06/04/06 10:35:55 INFO [oracle.sdovis.SRS] loadding SRS information from MDSYS.cs_srs (srid=32771).
06/04/06 10:35:55 WARN [oracle.sdovis.util.Util] Exception while transforming input MBR: java.sql.SQLException: ORA-13300: Single point transform error
ORA-06512: at "MDSYS.SDO_CS", line 23
ORA-06512: at "MDSYS.SDO_CS", line 43
06/04/06 10:35:55 ERROR [oracle.sdovis.theme.itp] Conversion of SRIDs returned null.
06/04/06 10:35:55 INFO [oracle.sdovis.DBMapMaker] **** time spent on loading features: 141ms.
Map Request:
<map_request
datasource="devtest4030"
srid="32771"
width="463"
height="404"
bgcolor="#a6caf0"
antialiase="true"
format="JAVA_IMAGE_COMPRESSED">
<center size="0.0025">
<geoFeature>
<geometricProperty typeName="center">
<Point>
<coordinates>37.5383,55.6605</coordinates>
</Point>
</geometricProperty>
</geoFeature>
</center>
<themes>
<theme name="image_theme_test">
<jdbc_image_query
image_column="BASEMAP"
image_mbr_column="GEO"
image_format="GIF"
jdbc_srid="8307"
datasource="devtest4030"
asis="false">SELECT BASEMAP,GEO FROM geo_raster</jdbc_image_query>
</theme>
</themes>
</map_request>
Test Result: Error during transformation to projected coordinate system
==================================================================
TEST#5 (MapViewer 10, predefined theme)
Now I`m adding one predefined image theme
<?xml version="1.0" standalone="yes"?>
<styling_rules theme_type="image" image_column="BASEMAP" image_format="GIF" image_resolution="2" image_unit="M">
<rule >
<features style=""> n = 2 </features>
</rule>
</styling_rules>
And trying to add it on my map
mv.deleteAllThemes();
mv.addPredefinedTheme("D2292C6");
mv.run();
Then I tried all Tests #1 - #4 with predefined theme. Results absolutely same as for dynamic theme.
==================================================================
TEST #6 (MapViewer 11)
Now I`m tried all above tests with MapViewer 11 version.
Tests Result:
1) When Im trying to set up projected CS (master SRID) – I receive similar error as in Test #3.
2) Without trying to set up master SRID I cannot receive not distorted image.
Generated image width twice bigger than height with any value of allow_local_adjustment
As I mentioned above the size of one degree of latitude two times bigger than size of one degree of longitude (at 55 degree North latitude).
May be this is the reason why MapViewer transform original map image stretching it by horisontal axis.
My main question is How I can receive correct map picture wich takes into account differencies in sizes of 1 degree latitude and longitude?