A- You ask Arcmap to load the layer and you see a\nwarning message: \u00ab\u00a0<\/em> The\nfollowing added data sources do not have spatial reference information.<\/em>\nThis data can be displayed in ArcMap, but it cannot\nbe projected.<\/em> \u00ab\u00a0<\/em>\n B- You ask Arcmap to load the layer and, without receiving\nany warning or error message, you do not see your new data, or it is in a\ndifferent place from where it should be. Search procedure<\/strong>\n<\/p>\n\n\n\n In this article we try to supply you a guide to\ndetermine the projection<\/a> system of a GIS data layer, when it is unknown.\n<\/p>\n\n\n\n We have limited ourselves to the most commonly used systems in France by the\nvarious organizations and administrations: Lambert and Lambert93 projections,\nUTM projections and non-projected data (geographical latitude \/ longitude).\n<\/p>\n\n\n\n Of course, there are many others, used punctually.\nBut it is impossible to determine them without a truly\ndetective work. We assume that you know how to use ArcGis and that\nyou have other reference data that will allow you to compare and assess the results.\n<\/p>\n\n\n\n You can download the pdf document of this article on\nthe NASCA<\/a>\nwebsite , by clicking here\n. <\/p>\n\n\n\n You must find the\nrange of X and Y values \u200b\u200bin the data.<\/strong> <\/p>\n\n\n\n 1- Start ArcMap with a new empty document The term coordinate system can be applied to data\nexpressed in decimal degrees (geographic coordinates) or a projected coordinate\nsystem expressed in meters. If the coordinates shown in the Range are of the\norder of hundreds of thousands or millions, they are meters. The data system will be searched in the section \u201c ArcGis\nProjected coordinate systems \u201c, and it will also remain to find the data geodesic system (Datum).\n<\/p>\n\n\n\n How to find the\nprojection system<\/strong> <\/p>\n\n\n\n Here you will find a logical progression based on\nthe value range of your layer. In addition to\nthese values, we will use the data area against three maps. Map\nN \u00b0 1: NTF Lambert zones<\/strong><\/p>\n\n\n\n Map N \u00b0 2: Lambert 93 areas<\/strong><\/p>\n\n\n\n Map N \u00b0 3: UTM time zones<\/strong><\/p>\n\n\n\n Y coordinates <1,000,000<\/strong> If you follow this procedure to find the coordinate\nsystem for QGis, it’s time to go back to the article How\nto find the coordinate system of a layer in QGis?<\/a> by clicking here<\/a>\n<\/p>\n\n\n\n How to find the\ngeodetic system (DATUM)<\/strong> <\/p>\n\n\n\n Once you have gone through the first two stages, you\nhave one last point to determine. Any location\nsystem necessarily refers to a center of the Earth. Since the Earth is not a perfect sphere, and that it is\nnecessary to calculate its center, there are several ways to calculate it and, therefore,\nseveral different \u00a0\u00bb centers\n \u00ab\u00a0. The\ndifference is not huge and until a few decades ago it was a rather theoretical\ndiscussion, the resulting positioning difference being generally less than\n300m. <\/p>\n\n\n\n Technically, a coordinate system is always\nassociated with a geodetic system. For UTM projections 30 to 32, in theory, the\nassociated system is the WGS84 systems. But they\ncan also be associated with the Europe 50 system. How to find out? Load the layer in ArcMap. -and the data appears in the\nright place and there is no slight shift (100-300m), you’re done. The definition you have adopted is the right one. <\/p>\n\n\n\n -and you have an offset of all\nyour entities, of the order of 100 to 300m, your data is not in WGS84. The coordinate system (UTM or geographic) is good, but your\ndata is not in WGS84. It must be in Europe 50 or\nNTF. \n\nOn\nthe other hand your reference data is in WGS84, if no message appears. \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nYour\nreference layer is not in WGS84. It is necessary to configure the transformations, if not,\neven if everything seems correct, in fact it will be wrong. \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nor If the data appears in the right place and there is\nno slight shift (100-300m), you are done. The\ndefinition you adopted (WGS84) is the right one. Usually, all layers of geographic data have the description of the coordinate system. Unfortunately, this is not always the case. Generally, the problem increases by not being able to contact the producer of the data. Problem…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"give_campaign_id":0,"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"sfsi_plus_gutenberg_text_before_share":"","sfsi_plus_gutenberg_show_text_before_share":"","sfsi_plus_gutenberg_icon_type":"","sfsi_plus_gutenberg_icon_alignemt":"","sfsi_plus_gutenburg_max_per_row":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[1260],"tags":[],"class_list":["post-7950","post","type-post","status-publish","format-standard","hentry","category-non-classe-en"],"aioseo_notices":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p6XU0A-24e","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/7950","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/comments?post=7950"}],"version-history":[{"count":0,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/7950\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/media?parent=7950"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/categories?post=7950"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/tags?post=7950"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nIf it is a vector data layer (points, lines, polygons),\nthe data must lack a defined coordinate system. In\nthe case of shapefiles, the PRJ file is missing. <\/p>\n\n\n\n\n\n\n\n
\nIf it’s a vector data layer (points, lines, polygons),\nthe data has a defined coordinate system, but it’s false. The PRJ file exists, but its contents are wrong. <\/p>\n\n\n\n
\nThe following maps show the different areas affected by\neach type of projection system. <\/p>\n\n\n\n
\n2- Add the data with the unknown coordinate system.\nThe data must not have a defined coordinate system.\nIn the case of shapefiles, it must not have PRJ files.\nIf there is one, rename it differently.
\n3- Right-click on the name of the layer in the table of\ncontents,
\n4- Click Properties to open the Layer Properties dialog\nbox.
\n5- Select the Source tab and examine the data range.\n(In the upper part of the window) <\/p>\n\n\n\n
\nIf the coordinates shown in the Range are expressed in\ndecimal degrees, they will range from -180 to +180 for longitudes ( Left<\/strong>\nand Right<\/strong> values ) and between -90 and +90 for latitudes ( High<\/strong>\nand Low<\/strong> values ). . The data system will\nbe searched in the section \u201c ArcGis Geographic\nCoordinate Systems\u201d. It remains to find the data geodetic system (Datum). (See further) <\/p>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/www.sigterritoires.fr\/wp-content\/uploads\/2019\/01\/311.png?resize=341%2C502&ssl=1\")
<\/figure>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/www.sigterritoires.fr\/wp-content\/uploads\/2019\/01\/312.png?resize=525%2C502&ssl=1\")
<\/figure>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/www.sigterritoires.fr\/wp-content\/uploads\/2019\/01\/313.gif?resize=525%2C319&ssl=1\")
<\/figure>\n\n\n\n
\n—- X coordinates between 0 and 1 100 000<\/em>\n
\n—— See map N \u00b0 1
\n——- If your data is in Lambert I zone
\n——– Data is in NTF Lambert I zone, EPSG code\n27561.
\n——- If your data is in Lambert II zone
\n——– Data is in NTF Lambert II area, EPSG code\n27562. –
\n——- If your data is in Lambert III zone
\n——– Data is in NTF Lambert III area, EPSG code\n27563.
\n—— If your data is in Lambert IV zone
\n——– Data is in NTF Lambert IV zone, EPSG code\n27564.
\nY coordinates between 1,000,000 and 2,000,000<\/strong>\n
\n—– X coordinates between 0 and 1 100 000<\/em>\n
\n—— See map N \u00b0 1
\n——- If your data is in Lambert I zone
\n——– Data is in NTF Lambert I carto, EPSG code\n27571.
\n—– X coordinates between 1,000,000 and 2,500,000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data is in zone 1 (green)
\n——– Data is in Lambert CC42 RGF, code EPSG 3942.\n
\nY coordinates between 2,000,000 and 3,000,000<\/strong>\n
\n—– X coordinates between 0 and 1 100 000<\/em>\n
\n—— See map N \u00b0 1
\n——- If your data is in Lambert II zone
\n——– The data is in NTF Lambert II carto, code EPSG\n27572
\n——- If your data is outside the Lambert II zone\n
\n——– Data is in NTF Lambert II extended, EPSG code\n27572.
\n—– X coordinates between 1,000,000 and 2,500,000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data is in zone 2 (blue)
\n——– Data is in Lambert CC43 RGF, code EPSG 3943.\n
\nY coordinates between 3,000,000 and 4,000,000<\/strong>\n
\n—– X coordinates between 0 and 1 100 000<\/em>\n
\n—— See map N \u00b0 1
\n——- If your data is in Lambert III zone
\n——– Data is in NTF Lambert III carto, code EPSG\n27573.
\n—– X coordinates between 1,000,000 and 2,500,000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data is in zone 3 (green)
\n——– Data is in Lambert CC44 RGF, code EPSG 3944.\n
\nY coordinates between 4,100,000 and 4,300,000<\/strong>\n
\n—– X coordinates between 500,000 and 600,000<\/em>\n
\n—— See map N \u00b0 1
\n——- If your data is in Lambert IV zone
\n——– Data is in NTF Lambert IV carto, code EPSG\n27574.
\nY coordinates between 4,000,000 and 5,000,000<\/strong>\n
\n—– X coordinates between 200,000 and 750,000<\/em>\n
\n—— See map N \u00b0 3
\n——- If your data is in Time Zone 30
\n——– Data is in WGS84 UTM 30N, EPSG code 32630.\n
\n——- If your data is in Time Zone 31
\n——– Data is in WGS84 UTM 31N, EPSG code 32631.\n
\n——- If your data is in Time Zone 32
\n——– Data is in WGS84 UTM 32N, EPSG code 32632.\n
\n—– X coordinates between 1,000,000 and 2,500,000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data is in zone 4 (blue)
\n——– Data is in Lambert CC45 RGF, code EPSG 3945.\n
\nY coordinates between 5,000,000 and 6,000,000<\/strong>\n
\n—– X coordinates between 200,000 and 750,000<\/em>\n
\n—— See map N \u00b0 3
\n——- If your data is in Time Zone 30
\n——– Data is in WGS84 UTM 30N, EPSG code 32630.\n
\n——- If your data is in Time Zone 31
\n——– Data is in WGS84 UTM 31N, EPSG code 32631.\n
\n——- If your data is in Time Zone 32
\n——– Data is in WGS84 UTM 32N, EPSG code 32632.\n
\n—– X coordinates between 1,000,000 and 2,500,000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data is in zone 5 (green)
\n——– Data is in Lambert CC46 RGF, EPSG code 3946.\n
\nY coordinates between 6,000,000 and 7,000,000<\/strong>\n
\n—– X coordinates between 0 and 1 250 000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data IS<\/strong> in zone 6 (blue)
\n——- There are two possibilities, you will have to\ntest them against a
\n——- known layer to determine which is the right one.\n
\n——– Data may be in Lambert RGF 93, code EPSG\n21546.
\n——–Or
\n——– Data may be in Lambert CC47 RGF, EPSG code\n3947.
\n——- If your data is NOT<\/strong> in zone 6 (blue)\n
\n——– Data is in Lambert RGF 93, code EPSG 21546.\n
\n—– X coordinates between 1,250,000 and 2,500,000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data is in zone 6 (blue)
\n——– Data is in Lambert CC47 RGF, code EPSG 3947.\n
\nY coordinates between 7,000,000 and 8,000,000<\/strong>\n
\n—– X coordinates between 1,000,000 and 2,500,000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data is in zone 7 (green)
\n——– Data is in Lambert CC48 RGF, code EPSG 3948.\n
\nY coordinates between 8,000,000 and 9,000,000<\/strong>\n
\n—– X coordinates between 1,000,000 and 2,500,000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data is in zone 8 (blue)
\n——– Data is in Lambert CC49 RGF, code EPSG 3949.\n
\nY coordinates between 9,000,000 and 10,000,000<\/strong>\n
\n—– X coordinates between 1,000,000 and 2,500,000<\/em>\n
\n—— See map N \u00b0 2
\n——- If your data is in zone 9 (green)
\n——– Data is in Lambert CC50 RGF, code EPSG 3950.\n<\/p>\n\n\n\n
\nThe Lambert 1,2,3,4 and extended 2 projections are\nalways associated with the NTF system (Nouvelle triangulation fran\u00e7aise)\n
\nThe Lambert 93 and CC42 to 50 projections are still\nassociated with the RGF system.
\nSo, if in the previous step you have come to define one\nof these projections, the work is finished. <\/p>\n\n\n\n
\nIn the case of geographical (non-projected) data, it\nis, also generally, associated with the WGS84 system, but can also be found\nassociated with the NTF or Europe 50 system. <\/p>\n\n\n\n
\nIt is necessary to have a data reference layer, with\nthe projection system defined correctly and above all, having a good accuracy\n(detail).
\nIn a new project in ArcMap, load this reference layer.\n
\nOpen the properties of the layer-> Source and note\nthe geodetic system (DATUM) of this layer: you will find it at the very bottom\nof the Data Source window.
\nIn ArcCatalog, set the unknown layer coordinate system\nas determined in the previous steps, using the most common geodetic system:\nWGS84 <\/p>\n\n\n\n
\nIf you have no message,<\/strong> <\/p>\n\n\n\n
\nIf your entities are shifted downwards (SW) by about\n230m, your layer is in NTF.
\nIf your entities are shifted upwards (NE) by about\n130m, then your layer is in Europe 50.
\nRemove the ArcMap layer. In ArcCatalog go to Layer Properties and XY Coordinate\nSystem, double click on the coordinate system. The\nsystem edit window opens. Click edit and go to\n\u00a0\u00bb Geographic Coordinate Systems\n \u00bb->\u00ab Europe\n and click on either NTF (Paris) or Europe Datum\n1950.
If you have a warning message,<\/strong><\/p>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/www.sigterritoires.fr\/wp-content\/uploads\/2019\/01\/314.png?resize=448%2C406&ssl=1\")
<\/figure>\n\n\n\n
\nClick on the transformations button, open the window \u00ab\n using \u00bb and\nselect
NTF_Paris_To_WGS_1984<\/strong> if you are in NTF \n\n\n\n<\/p>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/www.sigterritoires.fr\/wp-content\/uploads\/2019\/01\/315.png?resize=444%2C555&ssl=1\")
<\/figure>\n\n\n\n
ED_1950_To_WGS_1984_1<\/strong> if you are in Europe 50\n \n\n\n\n<\/p>\n\n\n\n![\"\"](\"https:\/\/i0.wp.com\/www.sigterritoires.fr\/wp-content\/uploads\/2019\/01\/316.png?resize=442%2C621&ssl=1\")
<\/figure>\n\n\n\n
\nIf you are in NTF and the data is shifted by about\n230m, the unknown layer is also in NTF.
\nIf you are in NTF and the data is shifted about 80m,\nthe unknown layer is in Europe 50.
\nIf you are in Europe 50 and the data is shifted by\nabout 130m, the unknown layer is also in Europe 50.
\nIf you are in Europe 50 and the data is shifted by\nabout 80m, the unknown layer is in NTF. <\/p>\n","protected":false},"excerpt":{"rendered":"